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(Last Modified On 6/3/2013)
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(Last Modified On 6/3/2013)
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Family
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Compositae
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Contributor
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Robert E. Woodson, Jr., Robert W. Schery, W. G. D'Arcy, Thomas S. Elias, PhilipBusey, R. M. King, H. Robinson, Tod F. Stuessy, Judith M. Canne, David J. Keil, T. M.Barkley, Robert C. Gardner, Beryl Brintnall Simpson and A. Spencer Tomb
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Description
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Mostly herbs, sometimes shrubs, trees or vines, variously pubescent or glandular, sometimes glabrous; stems terete, sometimes winged or flattened into cladodes, sometimes fistulose. Leaves alternate, verticillate, or opposite, sometimes basal, rarely reduced to scales, spines, or wanting, simple or 2- to many-foliolate, entire or variously toothed, lobed or dissected; petioles present or wanting; the leaf bases sometimes decurrent or clasping; stipules wanting but pseudostipules sometimes present. Inflorescences cymose, racemose, paniculate, umbellate, or of solitary heads, the heads sometimes in indefinite aggregates; peduncles mostly present but sometimes wanting and the heads then often in glomerules; bracts often present; pedicels mostly present, sometimes bracteolate. Heads of 1-many florets (flowers) situated on a receptacle (torus), basally enclosed in an involucre and sometimes interspersed with paleas (chaff ), the floret arrangement radiate, disciform, discoid, or ligulate, the outer or inner florets sometimes sterile; involucral bracts few-many in 1-several similar, differentiated, or evenly graded series, free or connate, valvate or overlapping, those of the innermost series sometimes enfolding the florets; receptacle depressed, flat, globose, conical, or obsolete; paleas characteristic of some groups, flat or enfolding the florets,
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Habit
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herbs, sometimes shrubs, trees or vines
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Description
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from the inner (disc) florets, often with a straplike, entire, or denticulate corolla (ligule), the androecium usually wanting, the style branches 2, mostly slender, glabrate, the ovary fertile or not, sometimes 3-angled; inner (disc) florets mostly with tubular, variously expanded, 4-5-lobed corollas, sometimes somewhat zygo- morphic, the anthers mostly oblong, marginally connate, introrse with sterile tips, basally blunt or tailed, the style branches 2, pubescent, glabrate or glandular, the ovary terete or compressed, often with an apical nectary. Fruit usually an achene, rarely baccate or drupaceous, or a utricle formed by fusion of the achene with paleas, bracts or other parts, the pericarp mostly hard; pappus usually present, of bristles, awns, or scales; sometimes with a distinct carpopodium.
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Note
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The Compositae vies with the Orchidaceae and Gramineae as the largest vascular plant family, with some 30,000 species and over 1,000 genera. It is also one of the most easily recognized and widespread of flowering plant groups. The family is well represented in temperate regions with large numbers of species in most dry areas. In the New World, diversity is especially great in Mexico and Peru, and upland Panama hosts many species related to groups from these regions. In the lowlands there are many widespread weeds. Many species from the forests have been recently elucidated. In Panama the tribes Eupatorieae and Heliantheae together constitute more than half the species present. The Eupatorieae includes many species with special adaptations such as epiphytism, scandent habit, and perhaps tolerance to shade that permit survival in forests. A number of species are trees. The tribe is mainly New World in distribution. Of the 83 Panamanian species, 24 are now known as endemics. Panamanian members of the Heliantheae are often widespread weeds of disturbed or open situations and many derive from groups better represented in Mexico. Although contiguous with other countries having a rich development of Compositae, Panama is not always a corridor in a continuum of species linking neighboring areas. For example, 37 species of Baccharis have been reported for Colombia but only 2 are known in Panama, and Gibson (personal communication) has identified 20 species of Vernonia in Guatemala but only 6 species are known in Panama. In spite of its large number of species and widespread occurrence, members of this family are of relatively little economic importance. In Panama a number of species are cultivated for ornament and some of these are sold as cut flowers in markets. Pluchea carolinensis (salvia) is widely cultivated as a medicinal, and Lactuca sativa (lettuce) is grown for salads. Many species are noxious weeds of cultivation and pastures. The major tribal categories in the Compositae are fairly well agreed upon with the majority of workers accepting 12 or 13 tribes. There is some disagreement as to the placement of particular genera, and proposals have recently appeared (e.g., Robinson & Brettell, 1973a, 1973b, 1973c) to base distinct tribes on some of the genera of anomalous placement. The genus Liabum is here treated with the Senecioneae, Isocarpha with the Eupatorieae, Schistocarpha with the Senecioneae, and Trichospira with the Heliantheae. Jaegeria and Sabazia are treated in subtribe Galinsoginae of the Heliantheae instead of in subtribe Helianthinae where they have often been placed. The traditional tribe Helenieae has long been subject to question, and genera occurring in Panama which were earlier referred to the Helenieae are treated here in the Tribe Tageteae. They are not closely related to other genera usually placed in the Helenieae and they are perhaps not closely related to other tribes. No tribe can be considered ancestral to the rest of the family but several tribes have been proposed as primitive stocks: Vernonieae (Augier & Du Merac, 1951), Senecioneae (Small, 1917-1919), Heliantheae (Cronquist, 1955), and Cardueae (Leonhardt, 1949). The 13 tribes commonly recognized in the family are often identified by the Roman numerals used by Bentham (1873a) and are employed here. Tribes IX (Calenduleae) and X (Arctoteae) do not occur in Panama. The arrangement of Panamanian genera into tribes is indicated in the following conspectus. The characters employed are merely synoptical and should not be relied upon for the determination of plants. An artificial key to genera follows. Each tribe is provided with a separate key to its constituent genera. Chromosome numbers cited in the text are reported either in literature indicated or in the series of general compilations (Cave, 1956-1964; Darlington & Janaki Ammal, 1945; Darlington & Wylie, 1955; Keil & Stuessy, 1975; Moore, 1968-1970; Ornduff, 1965-1967; Powell & Turner, 1963; Turner & King, 1964; Turner & Flyr, 1966). REED, cited occasionally as repository for plant specimens, indicates the private herbarium of Clyde F. Reed, 10105 Harford Rd., Baltimore, Md. U.S.A. Unless otherwise indicated, all illustrations are of Panamanian collections. MORPHOLOGY Plants of the Compositae display a range of specialized morphology not found in other families, and terminology is often particular to the family. A hand lens or dissecting microscope is useful in examining these plants and some features must be studied with a compound microscope. Literature citations in the following survey of terminology refer mainly to good illustrations of Compositae structures. Pubescence and glands.-Characteristic hair (trichome) types (Fig. 1) are found in several groups of Compositae. In the Vernonieae hairs are sometimes sturdy, elongate and single-celled. In the Eupatorieae and Astereae hairs are usually many-celled and uniseriate or moniliform, with the basal or apical cell sometimes slightly differentiated. Arachnoid hairs, too fine to be seen in cellular detail under magnifications less than x45, occur and may form tomentum in the Inuleae, Senecioneae, and Cardueae. A specialized "verrucose hair" occurs in many genera of the Heliantheae. This hair consists of a multicellular basal rosette, one or two sturdy, distinctly verrucose, erect cells and an apex of one or two smooth, acicular cells. The basal rosette of cells is sometimes calcified giving the leaf a punctate appearance, and the sometimes calcified rugose and apical cells may result in a scabrous leaf surface. Large multiseriate hairs occurring in Trixis, Hieracium, Pectis, etc. may be termed bristles. Branched hairs occur on Hieracium. For a discussion of the double hairs (Zwillingshaare) found on the ovaries of many genera and especially of some primitive elements see Hess (1938).
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Note
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Conspicuous, often pellucid oil glands of various shapes are arranged charac- teristically on leaves and involucres in the Tageteae (Figs. 90, 93). In Sigesbeckia (Fig. 70), Hieracium (Fig. 107), and Sonchus (Fig. 109), large globose glands are displayed on bristles. In Baccharis, a coating of glandular material may make the leaf shiny. With the aid of a lens, punctate glands in the leaf surface or globose glandular materials on the surface may be observed in many species. Laticifers, completely internal to the epidermis, are visible with effort as irregular areas of differentiated surface in the leaves of Critonia daleoides. The sap of this species is clear. In the Lactuceae a network of laticifers invisible without special techniques yields copious milky sap. Leaf arrangement.-In Panama leaves are opposite or rarely verticillate in most Eupatorieae, Tageteae, many Heliantheae, and in Liabum and Schistocarpha (both Senecioneae), but are alternate in all other groups. Plants with leaves in basal rosettes belong to groups with alternate leaves. In plants with opposite leaves, it is not unusual for some leaves and branches in the region of the inflorescence to be alternate. The converse obtains in Trichospira where leaves in the inflorescence are opposite and in the rest of the plant alternate. Both Verbesina and Ambrosia are known in Panama only by alternate-leaved species but opposite-leaved species occur in nearby countries. Decachaeta is the only genus in the Eupatorieae with entirely alternate leaves. Involucral bracts (phyllaries).-These are mostly numerous and in most groups are overlapping in several graded series. Except in the Eupatorieae this is referred to as imbricate, but in the Eupatorieae the terms eximbricate, subimbricate, and imbricate are used to refer to degrees of overlapping. Good examples of these conditions are Ageratina anisochroma (Fig. 12), Bartlettina (Fig. 16), and Chromolaena odorata (Fig. 18), respectively. In some species of Tageteae, Senecioneae, Mutisieae, and Lactuceae the bracts do not overlap but are valvate, touching only at the margins (Fig. 110), or they may sometimes be marginally connate for part of their length. A whorl of short bracts at the base of the involucre (Fig. 110) may be referred to as either outer involucral bracts or as calyculate bracts. Commonly one or more subinvolucral bracts may be found on the pedicel, sometimes in a different phyllotaxy from the rest of the plant. In the Elephantopodinae the involucral bracts are decussate, and in these genera with their heads fused into a common receptacle, a series of subinvolucral bracts (Fig. 10) forms a pseudoreceptacle around the glomerule. Paleas (chaff) and receptacle (torus).-Convention refers to bracts external to the outermost whorl of florets as involucral bracts and those internal to it as paleas. Although artificial, this distinction causes little difficulty. The two structures are homologous with leaves but the paleas are usually considerably more modified. Paleas are best developed in the Heliantheae and Mutisieae but isolated species or genera of the Eupatorieae, Astereaei, Senecioneae, and Lactuceae and perhaps other tribes also have paleas. In the Heliantheae the paleas frequently enfold the ovary (Fig. 53c, 76c) and may be bent over the corolla in bud or occasionally are apically modified into awns or cusps. The paleas of Eclipta, Cirsium and Liabum are narrowed into bristles or awns. In many genera paleas are reduced to hairs or low scales which may persist on the receptacle. In some genera, low hairs or spicules on the receptacle are referred to as paleas although they may consist of enations of the receptacle, or remains of carpopodia and are not homologous with the bracts noted above. Aged receptacles may be fimbrillate (fringed), pilose, foveate (pitted), verrucose (warty or knobby), alveolate (honeycombed), spiculiferous, muricate (spiny), or naked (lacking paleas). The receptacle tissue may be completely sclerified or include parenchyma. Corollas.-Corollas (Hoffman 1894: 99, 101; Solbrig 1963b: 451; Bentham 1873b: tab. 8) are considered to be either ligulate (rays) or tubular (disc), although the tubular form includes modifications to campanulate, funnelform, etc., and ligulate corollas usually consist of a tube and a straplike ligule. When extremely narrow, corollas are termed filiform or capillary (Fig. 34E). The outline made by the top of the corollas and paleas is referred to as the disc. In the Lactuceae all corollas have a 5-lobed ligule. In other groups, ligulate corollas are confined to the outer whorls of florets on the head or are lacking. In the Mutisieae (Figs. 104, 106), ligulate corollas have a 4-lobed ligule and a short, opposing lobe at the top of the tube (bilabiate). In the Astereae, Inuleae, Heliantheae, Tageteae, Senecioneae and Anthemidae, ligules are 2-3-lobed or entire (Figs. 34B, 48B, 81A, 93B, 98B), and an opposing lobe is seldom present. In Zinnia (Fig. 58C) and Heliopsis (Fig. 57C) (Heliantheae) the corolla consists of a ligule persistent on the achene and a tube is lacking, and in Melampodium also the tube may be obsolete. Ligulate corollas are lacking in all Panamanian taxa of Vernonieae, Eupatorieae, and Cardueae and only tubular corollas are present. Tubular corollas consist of a basal tube, an expanded limb, and 4-5 apical lobes. They are mostly actinomorphic but sometimes one suture of the limb is deeper than the others and in other cases two sutures are deeper, producing slightly bilabiate corollas. In the Eupatorieae attention has been drawn to the systematic impor- tance of cell outline in the corolla lobes; bulging cells can often be seen at x10-x50 magnifications but sinuous walls are visible only under a compound microscope after the special preparation of the tissue described by King & Robinson (1970). Sexual condition.-Sexual condition of the florets is of great systematic utility. In the Vernonieae, Eupatorieae, and Cardueae (Panama) and in a few genera in other groups, all florets are alike, perfect, and have tubular corollas. Such heads are termed discoid. All florets of the Lactuceae are also perfect and have only ligulate corollas. These heads are termed ligulate. In the above mentioned groups all florets are fertile, producing mostly viable achenes. In most other groups, the outer florets are pistillate, lack stamens, and only rarely produce staminodes. The outer florets may have tubular or ligulate corollas and the heads are termed radiate or disciform depending on whether the ligules are elongate (exceeding the stigmas and pappus) or short and inconspicuous. The ovaries may be fertile or sterile. Florets toward the center of such heads are morphologically perfect with tubular corollas and-functional stamens. The ovaries may be fertile or sterile. Variations in the above conditions occur in a few groups. Some Mutisieae have two peripheral whorls of pistillate florets, the outer with ligulate corollas and the inner with tubular corollas. Whorls internal to these have perfect florets with tubular corollas. In a few cultivated plants, e.g., some strains of Dahlia, Chrysan- themum, and Tagetes, proliferation of pistillate, often abortive, florets with ligulate corollas may supplant normal florets with tubular corollas. Stamens.-Stamens (Fig. 1, Hoffman, 1894: 104; Bentham, 1873b: tab. 9) are usually of the same number as the corolla lobes. Filaments are usually com- pressed and the anthers are connate or coherent into a narrow tube. The anther apex is usually sterile and differentiated into a distinct, hyaline appendage. In Piquiera, Eclipta, and Eleutheranthera the appendage is much reduced or wanting. In the Mutisieae and in Youngia (Lactuceae) the anther apex is sterile but not demarcated on the dorsal (outer) side, appearing as a homogeneous continuation of the thecas. Anther bases may be blunt, auriculate, sagittate, or with variously elaborated tails. The auricles of adjacent anthers are sometimes united. In some cases short auricles appear to be derived from longer but crumpled tails. Tails are present in most taxa of Inuleae and Mutisieae. The order in which tribes are usually treated roughly follows the degree of elaboration of the anther bases. A ring or region of specialized cells near the top of the filaments, the anther collar (Figs. 1, 12-33), acts as a hinge to permit straightening of the filaments at anthesis when the style pushes through the anther tube with much of the pollen. Characteristics of the anther collar have been used systematically in the Eupatorieae and Senecioneae. Exothecial cells of the anthers, visible under a compound microscope after special preparation, have also been of systematic use in the Eupatorieae (King & Robinson, 1970). Styles.-The style (Hoffman, 1894: 107, 109, 110; Bentham 1873b: tab. 10; Solbrig, 1963b: 443; Gleason, 1952: 324) is typically a 2-branched shaft which may have an expansion (node) near the base (Figs. 12D, 75E). The basal expansion occasionally acts as a nectary and sometimes it is stipitate above the ovary by a slender pedicel. The base of the shaft is frequently immersed in a cupular nectary on the ovary apex (Fig. 34). In some species the branches do not separate and the shaft is entire. In most cases the dorsal (abaxial) surface is pubescent and the ventral (adaxial) surface is more or less flat. The stigmatic region is on the edge or ventral surface in a configuration characteristic of the tribe. Not always correlated with stigmatic position, several shapes of style branch are common (Fig. 1): Lactucoid: Branches slender, longitudinally uniform, and sparingly pubescent. The apex is acute or obtuse. This type occurs in the Lactuceae and in pistillate florets of other tribes. Vernonioid: Branches elongate, longitudinally uniform, and often copiously pubescent. This type occurs in the Vernonieae. Eupatorioid: Branches elongate, gradually expanded near the apex, minutely pubescent, papillose, or smooth. It is stigmatic at the margins near the base, and distal portions of the branches may be referred to as appendages. This type occurs in only the Eupatorieae (Figs. 11-33). Senecioid: Branches often short, truncate, the apex with a fringe of papillae or hairs (penicillate). This type occurs in some species of Senecioneae, Anthemideae, and Inuleae. Helianthoid: Branches are short, pilose near the apex, and sometimes with a triangular or filiform appendage at the tip. This type occurs in several genera of Astereae, Inuleae, and Heliantheae (Fig. 54C), and intergrades with the Senecioid type. Carduoid: Branches short and smooth, the shaft has an annulus of hairs or thickening near the apex. The type occurs in the Cardueae. Ovaries.-Taxonomic characters of the ovary are usually expressed in terms of the achene, and younger stages may be misleading. Wings in some Verbesina species do not develop until after anthesis, while in Wulffia the awn (pappus) is deciduous soon after anthesis. In many groups a cupular nectary (Figs. 33E, 75D, E) is present at the apex of the ovary and in some genera, e.g., Ayapana, it is conspicuous. This is distinct from the expanded style base which resembles a nectary in some groups (Figs. 12D, 75E). The nectary may be stipitate. It may envelop the basal enlargement of the style shaft or end below it, in which case the stylar expansion appears stipitate. The nectary and style shaft are adnate only at the base. In several tribes; Vernonieae, Eupatorieae, Inuleae, Tageteae, and Anthemideae, the ovaries are characteristically terete, often ribbed, while in the Astereae and Heliantheae they are often compressed laterally (radially) or dorsiventrally (tangentially). Fruits.-The usual dispersal unit in the Compositae is the achene, which consists of pericarp, endosperm and embryo, and sometimes includes a pappus, persistent nectary, and carpopodium. The pericarp (rind) is usually hard but is soft and fleshy in Wulffia. The exocarp is sometimes transparent. The achene may be apically narrowed into a beak (Fig. 108) which subtends the pappus, and the top of the beak may be expanded in a flange (Fig. 108). All structures surmounting the achene except the nectary are referred to as pappus. This may consist of hairs, bristles, scales (squamellae), awns or rarely glands, and sometimes these elements are fused in a corona or annulus (Fig. 66). Bristles or hairs are usually strigulose (barbellate, scabrid) and are especially fine and numerous in the Senecioneae and Lactuceae. Stout bristles are sometimes basally flattened or expanded. Scales may be lacerate (Fig. 9C). In the Heliantheae awns are common. While the pappus is of great utility in identifying Compositae, it is not unusual to find epappose (calvous) achenes in individuals or species of normally pappose groups. The carpopodium (hypophyses) is sometimes conspicuous (Figs. 19E, 106C), and the cellular arrangement has been given taxonomic weight in the Eupatorieae. A stipe arising above the carpopodium occurs in some species of Verbesina. In Unxia (Fig. 54) a notch appears on the achene at the carpopodium site. Frequently, the achene is united with enveloping bracts or paleas or with adjacent florets, and the compound structure falls together. This compound fruit may be termed a utricle in the same sense as the term is used in the Chenopodiaceae and Urticaceae. It has also been known as an involucral fruit or fruiting involucre. The utricle may be flat and winglike or samaroid as in Delila (Fig. 45), covered -with hooks or spines and burlike as in Acanthospermum (Fig. 47), or the bract may be tightly fused to and hardly distinguishable from the achene as in Melampodium (Fig. 52). In Sclerocarpus (Fig. 69) the surrounding bract is adnate to the achene apex but sometimes breaks free during dispersal. Several achenes (or heads) may be held in glomerules with associated bracts to form a burlike utricle in members of the Vernonieae (Fig. lOB). In a number of Panamanian Compositae the fruit is fleshy and bird-dispersed. The inulin-rich pericarp of Wulffia is soft and fleshy and this baccate fruit is technically a drupe. In Clibadium and Milleria (Fig. 46) parts of the involucre are fleshy or even juicy and form a baccate structure. The baccate condition is best noted in fresh material and may pass unnoticed when dry. Achene shape is sometimes indicative of tribe; thus the Heliantheae and Cardueae have generally larger achenes than those of other tribes and in the Lactuceae, Tageteae, and Mutisieae, fruits are often long and thin. Achenes are often compressed in the Astereae and Heliantheae and sometimes in the Lactuceae, but are mostly oblong and cylindrical in the Vernonieae, Eupatorieae, Inuleae, and Senecioneae. Winged achenes occur only in the Heliantheae.
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Reference
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Adams, C. D. 1963. Compositae. In J. Hutchinson & J. M. Dalziel (editors), Flora of West Tropical Africa. Ed. 2. Vol. 2: 225-297. Crown Agents for the Colonies, London. Aristeguietas, L. 1964. Compositae. In T. Lasser (editor), Flora de Venezuela. Vol. 10: 1-941. Instituto Botatnico, Caracas. Augier, J. & M. Du Merac. 1951. La phylogenie des composees. Rev. Sci. 89: 167-182. Baker, J. G. 1873-1884. Compositae. In C. F. P. von Martius (editor), Flora Brasiliensis. Vols. 6(2): 1-398; 6(3): 1-442. Fleischer, Leipzig. Bentham, G. 1873a. Compositae. In G. Bentham & J. D. Hooker, Genera Plantarum. Vol. 2: 163-533. Lovell Reeve, London. . 1873b. Notes on the classification, history and geographical distribution of Compositae. Jour. Linn. Soc., Bot. 13: 335-582. Blake, S. F. 1930. Notes on certain type specimens of American Asteraceae in European herbaria. Contr. U.S. Natl. Herb. 26: 227-263. Cassini, H. 1826-1834. Opuscules Phytologiques. Levrault, Paris. Candolle, A. P. de. 1836-1838. Compositae. In Prodromus Systematis Naturalis Regni Vegetabilis. Vols. 5, 6, 7 (part 1). Cave, M. C. (editor). 1956-1964. Index to plant chromosome numbers. Chapel Hill, North Carolina. Cronquist, A. 1955. Phylogeny and taxonomy of the Compositae. Amer. Midl. Naturalist 53: 478-511. Darlington, C. D. & E. K. Janaki Ammal. 1945. Chromosome Atlas of Cultivated Plants. George Allen & Unwin Ltd., London. & A. P. Wylie. 1955. Chromosome Atlas of Flowering Plants. Ed. 2. George Allen &-Unwin Ltd., London. Fedorov, A. A. (editor). 1969. Chromosome Numbers of Flowering Plants. Academy of Sciences of the U.S.S.R., V. L. Komarov Botanical Institute, Moscow. This content downloaded from 192.104.39.2 on Thu, 23 May 2013 12:03:50 PMAll use subject to JSTOR Terms and Conditions844 ANNALS OF THE MISSOURI BOTANICAL GARDEN [VOL. 62 Gibson, D. Nash, P. C. Standley & L. 0. Williams. in press. Compositae. In Flora of Guatemala. Fieldiana Bot. Gleason, H. A. 1952. Compositae. In The New Britton and Brown Illustrated Flora of the Northeastern United States and Adjacent Canada. Vol. 3: 323-545, 550-551. Hegi, G. 1916-1929. Compositae. In Illustrierte Flora von Mittel-Europa. Vols. 6 (1): 394-544; 6 (2): 1-1386. Hafner. New York. Hess, R. 1938. Vergleichende Untersuchungen fiber die Zwillingshaare der Compositen. Bot. Jahrb. 68: 435-496. Hoffman, 0. 1894. Compositae. In A. Engler & K. Prantl (editors), Naturlichen Pflanzenfamilien. Vol. 4(5): 87-375. Wilhelm Engelmann, Leipzig. Keil, D. J. & T. F. Stuessy. 1975. Chromosome counts of Compositae from the United States, Mexico and Guatemala. Rhodora 77: 171-195. King, R. M. & H. Robinson. 1970. The new synantherology. Taxon 19: 6-11. Leonhardt, R. 1949. Phylogenetisch-systematische Betrachtungen. I. Betrach- tung zur Systematik der Compositen. Oesterr. Bot. Zeitschr. 96: 293-324. Lessing, C. F. 1832. Synopsis Generum Compositarum. Dunker et Humbolt, Berlin. Moore, R. J. (editor). 1968-1970. Index to plant chromosome numbers. Regnum Veg. 68: 1-115; 77: 1-112; 84: 1-134. Ornduff, R. (editor). 1965-1967. Index to plant chromosome numbers. Regnum Veg. 50: 1-128; 55: 1-126; 59: 1-129. Powell, A. M. & B. L. Turner. 1963. Chromosome numbers in the Compositae. VII. Additional species from the southwestern United States and Mexico. Madronio 17: 128-140. Robinson, H. & R. D. Brettell. 1973a. Tribal revision in the Asteraceae III. A new tribe, Liabeae. Phytologia 25: 404-407. & . 1973b. Tribal revisions in the Asteraceae. IV. The relationships of Neurolaena, Schistocarpha and Alepidocline. Phytologia 25: 439-445. & . 1973c. Tribal revision in the Asteraceae. VIII. A new tribe, Ursineae. Phytologia 26: 76-85. - & . 1974. Studies in the Liabeae (Astereae). II. Preliminary survey of the genera. Phytologia 28: 43-63. Schulz, 0. E. 1911. Compositarum genera nonnulla. Symb. Antill. 7: 78-144. Seemann, B. C. 1852-1857. Pp. 433, in The Botany of the Voyage of H. M. S. Herald. Lovell Reeve, London. Small, J. 1917-1919. The origin and development of the Compositae. New Phytol. 16: 157-276; 17: 13-230; 18: 1-35, 65-89, 129-176, 201-234. Solbrig, 0. T. 1963a. Subfamilial nomenclature of Compositae. Taxon 12: 229-235. . 1963b. The tribes of Compositae in the Southeastern United States. Jour. Arnold Arbor. 44: 436-461. Turner, B. L. & D. Flyr. 1966. Chromosome numbers in the Compositae. X. North American Species. Amer. Jour. Bot. 53: 24-33. & R. M. King. 1964. Chromosome numbers in the Compositae. VII. Mexican and Central American species. Southw. Naturalist 9: 27-39.
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Key
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CONSPECTUS OF THE PANAMANIAN COMPOSITAE a. Heads with staminate or perfect florets towards the middle, the corollas tubular, 5-lobed; sometimes with pistillate florets towards the outside, the corollas tubular or ligulate; sap not milky. b. Anther tips with sterile, tonguelike, often hyaline appendages. c. Florets all alike, perfect, corollas tubular, not yellow; anthers not tailed; receptacle naked. d. Leaves alternate; style branches slender, terete, hairy all over, the style shaft apically hairy; anthers auricled; hairs oft...... Tribe I. Vernonieae p. 856 e. Heads all distinct ...... Subtribe A. Vernoniinae ee. Heads fused in glomerules in a common receptacle ...... Subtribe B. Elephantopodinae dd. Leaves mostly opposite (except sometimes in the region of the inflorescence); style branches gradually expanded near the tips, papillose or short-hairy, the style shaft often glabrous; anthers obtuse or rounded; hairs multicellular, often moniliform ...... Tribe II. Eupatorieae cc. Florets often not all alike, corollas often yellow; anthers sometimes tailed; receptacle naked or with paleas. f. Leaves mostly not spiny; involucral bracts not spiny; anthers tailed or not; style shaft without an apical ring. g. Leaves alternate; style branches flattened-fusiform, sometimes apically appendaged or rounded; anthers tailed or not; receptacle mostly naked; pappus mostly of bristles. h. Anthers obtuse; style branches often appendaged; achene often com- pressed; hairs multicellular ...... Tribe III. Astereae hh. Anthers tailed; style branches rounded; achene plump; hairs arachnoid -------------------------------------------Tribe IV . Inuleae p. 1033 gg. Leaves alternate or opposite; style branches flattened-fusiform, sometimes apically appendaged; anthers not tailed; receptacle with paleas or naked; pappus of bristles, awns, or scales. i. Pappus of awns, stiff bristles, or scales; style branches often appendaged. j. Involucre without transparent margins; leaves mostly opposite, often 3-nerved from the base or trifoliolate. k. Receptacle mostly with paleas enfolding the achenes; involucral bracts mostly unequal, overlapping; leaves mostly eglandular; hairs often verrucose ...... Tribe V. Heliantheae 1. Florets few; central florets abortive; receptacle naked ...... Subtribe A. M illeriinae 1.'' Florets many; central florets abortive; receptacle mostly with paleas ...... Subtribe B. Melampodiinae 1."' Heads discoid and unisexual, or radiate and central florets abortive ...... Subtribe C. Ambrosiinae 54. Ambrosia ...... 55. Parthenium 1."" Heads radiate, the corollas of the ray florets without a tube, persistent ...... Subtribe D. Zinniinae 1.""' Achenes laterally compressed; pappus often of awns ...... Subtribe E. Helianthinae 1.""". Achenes dorsiventrally compressed; involucral bracts biseriate ...... Subtribe F. Coreopsidinae l."""' Pappus of plumose awns or bristles ...... Subtribe G. Galinsoginae kk. Receptacle naked; involucral bracts equal, mostly valvate; leaves with oil glands; glabrate ...... Tribe VI. Tageteae jj. Involucre with hyaline, transparent, brownish margins; leaves alternate, with a strong midvein ...... Tribe VII. Anthemideaeii. Pappus of soft, silky, hairlike bristles; style branches not appendaged ...... Tribe VIII. Senecioneae ff. Leaves and involucral bracts spiny; anthers tailed; style shaft with an apical ring ...... Tribe XI. Cardueaebb. Anther tips sterile but not differentiated into hyaline, tonguelike appendages; anthers mostly tailed ...... Tribe XII. Mutisieae p. 1276 aa. Heads with only perfect florets, the corollas ligulate, 5-denticulate; sap milky ...... Tribe XIII. Lactuceae KEY TO THE GENERA 1. Leaves opposite (reduced leaves or bracts sometimes alternate near the inflorescence). 2. Leaves compound or deeply lobed. 3. Leaves and involucre with conspicuous oil glands ...... 92. Tagetes 3.' Leaves and involucre without glands. 4. Leaves simple with pointed lobes; achene subglobose or prismatic; pappus of fine bristles or wanting. 5. Achenes subglobose; pap...... 52. Polymnia 5.' Achenes oblong, prismatic, or 5-ribbed; pappus of bristles. 6. Pappus bristles fine, strigose; achene glabrous or pubescent; trees or shrubs; paleas absent ...... 28. Neomirandea 6.' Pappus bristles basally flattened or stout, plumose; achene copiously ascending-pilose; paleas present ...... 88. Tridax 4.' Leaves compound or if simple the lobes rounded; achene linear or compressed; pappus of barbed awns or wanting. 7. Heads large, the involucre more than 1 cm across; inner involucral bracts with broad, hyaline margins; trees or cultivated herbs ...... 80. Dahlia 7.' Heads smaller, the involucre mostly less than 1 cm across; involucral bracts with herbaceous margins; herbs, sometimes cultivated. 8. Vines climbing by hooked petioles; achene oblong; outer involucral bracts 5, slender, spreading...... 81. Hidalgoa 8.' Herbs or vines lacking hooked petioles; achene linear; outer involucral bracts various. 9. Achene with a distinct beak; leaves deeply dissected, more than 3 cm long ...... 79. Cosmos 9.' Achene without a distinct beak; leaves trifoliolate, or less than 3 cm long ...... 77. Bidens 2.' Leaves simple, not deeply lobed. 10. Fruit a simple, dry achene, not spiny, falling free from the head and involucral parts. 11. Pappus of 1-5 stalked knobs. 12. Corolla pilose near the lobes; heads with more than 10 florets; involucral bracts 10-20; anther appendages wider than long ...... 10. Adenostemma 12.' Corolla generally puberulent outside; heads usually with fewer than 10 florets; involucral bracts 7-8; anther appendages longer than wide ...... 30. Sciadocephala 11.' Pappus of bristles, scales, awns, or wanting, not of stalked knobs. 13. Pappus of numerous (more than 10) bristles or scales; paleas mostly wanting. 14. Involucral bracts fewer than 10. 15. Heads discoid; florets all alike, all with stamens. 16. Heads more than 15 mm tall, with 5 involucral bracts and numerous florets...... 91. Porophyllum 16.' Heads less than 10 mm tall, with 4 involucral bracts and 4 florets ...... 27. M ikania 15.' Heads radiate; outer florets lacking stamens ...... 90. Pectis 14.' Involucral bracts more than 10. 17. Involucral bracts 10-15 mm tall, oblong, blunt, with conspicuous dark, glandular streaks ...... 89. Dyssodia 17.' Involucral bracts not as above. 18. Pappus plumose, the bristles (scales) basally broad -88. Tridax 18.' Pappus not plumose (sometimes strigulose or barbellate). 19. Leaves strongly discolorous, green or brown and glabrate above, whitish, sometimes tomentose, beneath. 20. Florets yellow or white; leaves broad, felty-tomentose beneath ...... 96. Liabum 20.' Florets violet or white; leaves narrow, glabrous beneath. 21. Principal leaves more than 5 cm long; involucre manifestly pubescent; corolla tube slender, strongly expanded about halfway up ...... 11. Ageratina 21.' Principal leaves less than 5 cm long; involucre glabrate; corolla gradually broadening upward ...... 12. Ageratum 19.' Leaves concolorous, similar on both sides. 22. Receptacles paleaceous; corollas yellow or white; verrucose hairs often present. 23. Pappus bristles basally flat and broad; achenes pubescent ...... 84. Calea 23.' Pappus bristles slender; achenes glabrous ...... 98. Schistocarpha 22.' Receptacles naked; corollas white, pink, purplish, not yellow; hairs not of verrucose type, mostly moniliform. 24. Heads with fewer than 6 florets. 25. . Leaves copiously glandular beneath; small herbs ...... 18. Condylidium 25.' Leaves eglandular beneath; shrubs ...... 19. Critonia 24.' Heads with more than 6 florets. 26. All involucral bracts deciduous in age; involucre tubular, 5-8 mm tall, 2-3 times longer than broad, the bracts appressed, overlapping, the tips of the outermost differentiated and appearing as brown or green spots on the yellowish, striate involucre ...... 17. Chromolaena 26.' At least some involucral bracts persistent; involucre not as above. 27. Anther appendages shorter than wide, often inconspicuous. 28. Style branches with prominent, fusiform knobs at the tips; outer involucral bracts with more than 7 fine, elevated ribs; inner involucral bracts more than twice as long as the achene; vines ...... 22. Gongrostylus 28.' Style branches sometimes expanded apically but without knobs (expansion in only 2 dimensions); outer involucral bracts without fine, elevated ribs; inner involucral bracts only slightly exceeding the achene; herbs or shrubs ...... 26. Koanophyllon 27.' Anther appendages as long as wide or longer, mostly prominent. 29. Pedicels glabrous; involucral bracts narrow with broad, hyaline margins, glabrous; achene weakly 10-ribbed ...... 16. Brickellia 29.' Pedicels and inflorescence branches pubescent, mostly tomentose; involucral bracts mostly not as above; achene 2-6-ribbed. 30. Corolla slender, strongly expanded about halfway up; pappus bristles easily deciduous ...... 11. Ageratina 30.' Corolla gradually expanded upwards, the limb not sharply demarcated; pappus bristles persistent. 31. Heads large; involucral bracts more than 2 mm wide; receptacle more than 2 mm across; achenes more than 2.2 mm long. 32. Pedicels stout; achenes more than 2.5 mm long ...... 24. Heterocondylus 32.' Pedicels slender; achenes less than 2.5 mm long ...... 15. Bartlettina 31.' Heads smaller; involucral bracts less than 2 mm wide; receptacle less than 2 mm across; achenes mostly less than 2.2 mm long. 33. Most leaves less than 6 cm long (excluding petiole) ...... 21. Fleischmannia 33.' Leaves more than 6 cm long. 34. Receptacle hemispherical, hairy; corolla lobes pilose ...... 23. Hebeclinium 34.' Receptacle flat or weakly convex, glabrous; corolla lobes glabrous or pilose. 35. Leaves subsessile, the blade expanded abruptly (not always widely) above the short petiole; nectary large and conspicuous on the achene apex ...... 14. Ayapana 35.' Leaves petiolate, the blade basally acuminate; nectary mostly not prominent. 36. Involucral bracts 1 mm wide or less ...... 21. Fleischmannia 36.' Involucral bracts 1-2 mm wide. 37. Leaves copiously pubescent above; achene glandular 13. Austroeupatorium 37.' Leaves glabrate above; achene eglandular. 38. Corolla lobes pilose; heads with more than 20 florets ...... 15. Bartlettina 38.' Corolla lobes glabrous; heads with 8-12 florets ...... 19. Critonia 13.' Pappus of fewer than 8 bristles, scales, awns, or wanting; paleas mostly present. 39. Leaves copiously glandular beneath. 40. Heads radiate; florets bright yellow. 41. Large herbs or shrubs; leaves broad, pubescent; paleas conspicuous ...... 63. Montanoa 41.' Small herbs; leaves narrow, glabrate; paleas wanting ...... 90. Pectis 40.' Heads discoid; florets white or purplish. 42. Heads with 3-5 perfect florets; involucral bracts 3-5 ...... 31. Stevia 42.' Heads with more than 5 florets; involucral bracts 5. 43. Involucre longer than the disc; florets fewer than 12 ...... 59 . Eleutheranthera 43.' Involucre shorter than the disc; florets mostly more than 12. 44. Heads purplish; disc nearly flat; paleas wanting ...... 12. Ageratum 44.' Heads whitish; disc strongly convex or conical; paleas present ...... 25. Isocarpha 39.' Leaves eglandular beneath. 45. Outer involucral bracts 5, linear-spathulate, widely-spreading with conspicuous, stalked glands; verrucose hairs not present...... 68. Sigesbeckia 45.' Involucral bracts not as above; verrucose hairs often present. 46. Paleas linear, apically barbed ...... 58. Eclipta 46.' Paleas broader or wanting, not apically barbed. 47. Heads discoid; florets all alike. 48. Achenes with 2-3 prominent, ciliate angles. 49. Heads solitary on long peduncles, sometimes in loose, ill-defined aggregates; heads more than 6 mm across ...... 70. Spilanthes 49.' Heads in small, many-headed inflorescences; heads less than 6 mm across...... 66. Salmea 48.' Achenes terete, ribbed, or compressed, but not with 2-3 ciliate angles. 50. Heads with more than 15 involucral bracts; florets often more than 20. 51. Heads in well-defined inflorescences; paleas wanting. 52. Involucral bracts narrow, persistent; pedicels slender; erect, terrestrial plants ...... 12. Ageratum 52.' Involucral bracts broad, the inner series deciduous; pedicels stout; epiphytes on mangroves ...... 32. Tuberostylis 51.' Heads solitary or in loose, ill-defined aggregates; paleas present. 53. Achene compressed with definite angles; pappus of 2-8 caducous, strigose bristles; involucral bracts with blunt tips ...... 62. Melanthera 53.' Achene mostly without definite angles; pappus of scales or wanting; involucral bracts with narrow tips ...... 73. Viguiera 50.' Heads with fewer than 15 involucral bracts; florets mostly fewer than 15. 54. Pappus of two stout awns; leaves strongly discolorous, glabrous and drying dark above, grey tomentose beneath ...... 83. Trichospira 54.' Pappus of low scales or wanting; leaves concolorous, pubescent or glabrate. 55. Paleas present; corollas evenly pubescent ...... 60. Garcilassa 55.' Paleas wanting; corollas pilose on the tube, glabrate above ...... 29. Piqueria 47.' Heads radiate; florets differentiated. 56. Achenes dimorphic, the innermost linear with 2(3) stout awns, the outermost flat with laciniate margins ...... 82. Synedrella 56.' Achenes all alike, or if differentiated, the awns small and weak. 57. Heads small, less than 6 mm across; pappus mostly minute or wanting. 58. Herbs or shrubs more than 60 cm tall. 59. Heads white; heads in small clusters on pedicels mostly shorter than the heads; shrubs or large herbs. 60. Involucre biseriate; inflorescence of 10-30 heads ...... 50. Ichthyothere 60.' Involucre multiseriate; inflorescence of 10-800 heads ...... 49. Clibadium 59.' Heads yellow; heads mostly solitary on pedicels often much longer than the heads; tall herbs with slender branches ...... 48. Baltimora 58.' Herbs less than 60 cm tall or sprawling. 61. Outer bracts short with prominent white margins; leaves narrowly spathulate, serrate near the apex ...... 78. C hrysanthellum 61.' Outer bracts without white margins; leaves ovate or elliptical. 62. Petioles conspicuously long-pilose, the hairs eglandular; pedicels obscure, the heads subtended by a pair of large, foliaceous bracts; receptacle weakly convex ...... 53. Unxia 62.' Petioles glabrate or if pilose, the hairs gland-tipped; pedicels evident, foliaceous bracts mostly wanting; receptacle conical or convex. 63. Achenes sharply 2-3-angled, conspicuously ciliate ...... 70. Spilanthes 63.' Achenes eciliate, mostly plump, not angled. 64. Involucre with conspicuous, stout hairs; involucral bracts 1-2-seriate, narrow, but basally expanded; pedicel hairs eglandular ...... 86. Jaegeria 64.' Involucre sparsely pilose; involucral bracts 2-many- seriate, broad, not basally expanded; pedicel hairs often gland-tipped. 65. Heads with 3-8 ray florets; florets each enclosed by an involucral bract and 2-3 paleas ...... 85. Galinsoga 65.' Heads with 8-17 ray florets; florets not usually enclosed by involucral bracts ..... 87. Sabazia 57.' Heads larger, more than 6 mm across; pappus mostly present. 66. Achene angles or wings ciliate, not pubescent overall. 67. Achene with prominent, sturdy awns, sometimes winged ...... 76. Zexmenia 67.' Achene with weak, small awns or none, not winged ...... 70. Spilanthes 66.' Achene not ciliate, sometimes minutely strigose. 68. Pappus of prominent, persistent awns; achene winged only apically or not at all. 69. Upper leaves alternate, most leaves lobed; heads large (involucre more than 2 cm across) ...... 71. Tithonia 69.' All leaves opposite, not lobed; heads smaller. 70. Involucral bracts with slender, awnlike tips. 71. Achene sharply angled; ray florets fertile ...... 61. Lasianthaea 71.' Achene only slightly angled; ray florets sterile ...... 73. Viguiera 70.' Involucral bracts with blunt tips; ray florets sterile. 72. Achene evenly canescent or pilose with long hairs ...... 69. Simsia 72.' Achene glabrate ...... 64. Oyedaea 68.' Pappus various but not of prominent, persistent awns; if awns present, then the achene conspicuously winged. 73. Involucral bracts broadly rounded or truncate. 74. Achene smooth; corolla of the ray floret a sessile ligule (without a tube), persistent on the achene ...... 57. Zinnia 74.' Achene tuberculate (actually enfolded by an adnate involucral bract); corolla of the ray floret with a tube, falling before the achene matures ...... 51. Melampodium 73.' Involucral bracts pointed. 75. Outer involucral bracts ca. 5, foliaceous, often wide- spreading from the base; corolla tube of ray florets elongate. 76. Ray florets fertile; corolla of disc florets without black hairs; achenes falling free; verrucose hairs wanting; inflorescence a panicle ...... 65. Rumfordia 76.' Ray florets abortive; corolla of disc florets with black hairs near the apex; achenes enveloped by and falling with the palea; verrucose hairs present; inflorescence of solitary or loosely aggregated heads ...... 67. Sclerocarpus 75.' Outer involucral bracts more than 5, not wide-spreading except sometimes at the tips; corolla tube of ray florets mostly shorter than the achenes or wanting. 77. Ray corolla lacking a tube, persistent on the achene; pappus wanting ...... 56. Heliopsis 77.' Ray corolla with a tube, falling before the achene matures; pappus present or not. 78. High-climbing vine; achene epappose, unbeaked ...... 75. Wulffia 78.' Terrestrial herbs; achene with pappus often present, a small beak sometimes present. 79. Bracts narrow, straight ...... 73. Viguiera 79.' Bracts broad, curved ...... 74. Wedelia 10.' Fruit not falling as a simple, dry achene, either baccate or the achene united with the involucral bracts or palea and falling as a coalesced unit (utriculate), sometimes with hooks or spines. 80. Fruit thin with broad wings (flat, compressed bracts) ...... 45. Delilia 80.' Fruit plump, wingless. 81. Fruit achenelike with prominent hooks or spines (formed on the enveloping involucre); heads sessile ...... 47. Acanthospermum 81.' Fruits without hooks or spines; heads pedunculate. 82. Fruit baccate or drupaceous, the fleshy or soft-leathery tissues formed by the pericarp or involucre. 83. High-climbing vines; fruits free from the subtending, conspicuous, pointed paleas; ray florets numerous, showy ...... 75. Wulffia 83.' Erect, slender herbs or shrubs; fruits enclosed in a fleshy involucre; ray florets solitary or inconspicuous; paleas obscure or wanting. 84. Ray floret yellow, solitary; outer 2 involucral bracts fused and envelop- ing the achene and inner bracts ...... 46. Milleria 847- Ray florets white, several; outer involucral bracts separate, open apically ...... 49. Clibadium 82.' Fruit dry, formed by coalescence of the achene with involucral bracts or paleas. 85. Ligules copiously pubescent beneath; disc corollas apically black-pilose; foliaceous bracts below the heads (upper leaves) alternate ...... 67. Sclerocarpus 85.' Ligules glabrate beneath; disc corollas without black hairs; leaves and bracts all opposite ...... 51. Melampodium 1.' Leaves alternate or restricted to a basal rosette. 86. Leaf tips and involucre spiny ...... 100. Cirsium 86.' Leaves and involucre not spiny. 87. Involucre of numerous, broad, colored, strawlike, persistent bracts; cultivated ornamental with large (more than 3 cm across) showy heads ...... 41. Helichrysum 87.' Involucre not as above; heads mostly smaller. 88. Heads ligulate; florets perfect; corollas 5-denticulate, yellow or white; achenes conspicuously sulcate, often linear; pappus mostly of silky bristles; sap milky. 89. Pedicels tomentose; tawny hairs over 5 mm long conspicuous on leaves or stems; leaves mostly denticulate, not incised ...... 107. Hieracium 89.' Pedicels glabrate; tawny hairs over 5 mm long lacking (gland-tipped bristles sometimes present); leaves often incised. 90. Leaves mostly cauline; pappus of both fine hairs and bristles - 109. Sonchus 90.' Leaves in a basal rosette; pappus of bristles or fine hairs but not of both. 91. Heads less than 7 mm tall; inflorescence a many-headed, scapose panicle ...... 111. Youngia 91.' Heads more than 10 mm tall; inflorescence few-(or 1-)headed. 92. Leaves glabrate; inflorescences unbranched; paleas wanting ...... 110. Taraxacum 92.' Leaves copiously pubescent; inflorescences branched; paleas present ...... 108. Hypochoeris 88.' Heads radiate or discoid; florets mostly bisexual; corollas variously colored; achenes sometimes ribbed but seldom sulcate, seldom linear; pappus various; sap clear. 93. Anther tips sterile but not differentiated into distinct, hyaline, ligular appendages; anthers bases tailed, always present. 94. Scapose herbs, leaves restricted to a basal rosette; heads single. 95. Heads conspicuously radiate, the rays showy; heads more than 30 mm across; cultivated plant, not fruiting in Panama ...... 102. Gerbera 95.' Heads inconspicuously radiate or disciform; heads less than 20 mm across; native plants fruiting in Panama ...... 101. Chaptalia 94.' Leafy stemmed herbs, shrubs or vines, the stems leafy; peduncles borne on leafy stems, mostly in inflorescences. 96. Leaves subentire or inconspicuously denticulate; heads solitary or in few-headed (less than 10) inflorescences. 97. Heads solitary, large; involucre multiseriate, more than 20 mm long; florets orange or red ...... 104. Lycoseris 97.' Heads in several-headed inflorescences, smaller; involucre 1-2-seriate, less than 20 mm long; florets yellow ...... 106. Trixis 96.' Leaves prominently lobed; heads in many-headed inflorescences. 98. Erect herb or shrub; leaves glabrate above and lanate beneath; involucral bracts more than 10 mm long ...... 105. Onoseris 98.' Woody vine; leaves tomentose on each side; involucral bracts less than 10 mm long ...... 103. Jungia 93.' Anther tips sterile and differentiated into ligulate, hyaline appendages; anther bases mostly obtuse, rarely wanting. 99. Heads radiate, disciform, or unisexual; florets of at least 2 kinds. 100. Involucral bracts with distinct, brownish or yellowish, sometimes hyaline borders. 101. Leaves less than 12 mm wide; heads less than 15 mm across; creeping native plants ...... 78. Chrysanthellum 101.' Leaves more than 12 mm wide; heads more than 25 mm across; erect -cultivated plants ...... 93. Chrysanthemum 100.' Involucral bracts sometimes scarious-margined but without distinct borders. 102. Leaves compound, deeply divided or strongly 3-nerved from near the base. 103. Heads unisexual, the two sexes in different-appearing heads (non- functional parts present but much reduced). 104. Leaves deeply dissected, the segments narrow; staminate and pistillate heads on the same plant ...... 54. Ambrosia 104.' Leaves not dissected; staminate and pistillate heads on different plants (dioecious). 105. Heads discoid; involucre less than 10 mm tall ...... 35. Baccharis 105.' Heads disciform or radiate, the outer florets often few and inconspicuous; involucre more than 15 mm tall ...... 104. Lycoseris 103.' Heads perfect, both sexes present and functional in each head. 106. Involucre of valvate, weakly connate bracts, sometimes with an outer series of short, free bracts; pappus of numerous silky bristles. 107. Leaves entire; florets yellowish or whitish; woody vine ...... 99. Senecio 107.' Leaves toothed or lobed; florets pinkish or whitish; herb...... 95. Erechtites 106.' Involucre of several-seriate, overlapping, free bracts; pappus of awns, scales, or wanting, not of bristles. 108. Involucre more than 20 mm across; peduncles elongate, conspicuously thickened and fistulose apically ...... 71. Tithonia 108.' Involucre smaller; peduncles not conspicuously thickened apically or fistulose. 109. Inflorescence well-defined, composed of 10-800 heads; heads, exclusive of rays, less than 8 mm tall. 110. Leaves dissected; herbs to 1 m tall. 1 i0a. Ligules 5, less than 1 mm long, inconspicuous; outer involucre of 5 ovate bracts ...... 55. Parthenium li1a.' Ligules 8 or more, more than 2 mm long; involucre of numerous lanceolate bracts ...... 93. Chrysanthemum 110.' Leaves serrate or subentire, unlobed; shrubs or trees mostly over 1 m tall ...... 49. Clibadiaur, 109.' Inflorescence ill-defined, composed of a few aggregated heads; heads more than 10 mm tall. 111. Disc florets with black hairs near the apex; involucral bracts in 2 unlike series, the outer foliaceous, the inner shorter ...... 67. Sclerocarpus 111.' Disc florets without black hairs; involucral bracts nu- merous in several graded series. 112. Achene apically depressed between the awns; pappus of two stout, basally flattened, strigose awns ...... 69. Simsia 112.' Achene apically round or flat; pappus of awns and scales, of scales, or wanting, not of awns alone ...... 73. Viguiera 102.' Leaves simple, toothed or lobed, the sinuses not extending halfway to the midvein, mostly not 3-nerved from near the base, mostly pinnately veined with a single midvein or digitate with more than 3 veins. 113. Pappus of silky or strigose bristles. 114. Heads large, the involucre more than 3 cm across; achene and pappus bristles together more than 20 mm long ...... 104. Lycoseris 114.' Heads smaller; achene shorter. 115. Heads radiate, the peripheral florets pistillate and the ligules manifestly exceeding the style branches, pappus and disc florets. 116. Leaves reduced to scales or spines; midvein of involucral bracts slightly enlarged apically ...... 34. Aster 116.' Plants with normal, broad leaves, not spiny; midvein of involucral bracts not enlarged apically. 117. Achenes compressed; herbs; ray florets white, bluish, or purplish ...... 37. Erigeron 117.' Achenes terete; mostly shrubs or trees; all florets yellow or orange ...... 99. Senecio 115.' Heads disciform, the peripheral florets perfect (Archibac- charis) or the ligules not exceeding the style branches, pappus, and disc florets. 118. Achene compressed 2(3)-ribbed; anthers tailless. 119. Herbs; plants perfect, both staminate and pistillate florets functional in each head ...... 36. Conyza 119.' Shrubs or vines; plants dioecious, one sex not functional on each plant ...... 33. Archibaccharis 118.' Achene plump, sometimes 5-ribbed; anthers mostly tailed. 120. Leaves scabrous above; receptacles paleaceous; verrucose hairs present ...... 97. Neurolaena 120.' Leaves soft or smooth on both sides; receptacles naked; hairs not of verrucose type. 121. Involucre of an inner series of narrow, similar bracts more than 6 mm long and an outer (calyculate) series of minute, similar bracts. 122. Leaves entire; florets yellowish or whitish; woody vine ...... 99. Senecio 122.' Leaves toothed or lobed; florets pinkish or whitish; herb ...... 95. Erechtites 121.' Involucre of graded bracts in several series, the inner-most mostly 6 mm long, often broad. 123. Stems conspicuously winged; achene (with pappus) more than 6 mm long ...... 43. Pterocaulon 123.' Stems wingless or obscurely so; achene (with pappus) less than 6 mm long. 124. Involucral bracts narrow, acicular; leaves, including petiolar region, saliently dentate...... 391. Blumea 124.' Involucral bracts obtuse; leaves entire or serrate, entire in the petiolar region. 125. Heads glomerate, the pedicels obscure or wanting; leaves less than 10 mm wide, wooly beneath ...... 40. G naphalium 125.' Heads with evident pedicels; leaves more than 10 mm wide, puberulent or glabrate beneath. 126. Leaves with stalked glands beneath; nectary of the staminate disc florets small ...... 42. Pluchea 126.' Leaves sometimes glandular-punctate but without stalked glands; nectary of the solitary staminate disc floret much larger than the ovary ...... 44. Tessaria 113.' Pappus of awns, glands, scales, or wanting. 127. Pappus present, of awns or scales. 128. Achene prominently winged ...... 72. Verbesina 128.' Achene not or only indistinctly winged. 129. Shrubs; inflorescence well-defined and many-headed (10- 800 heads) ...... 49. Clibadium 129.' Herbs; inflorescence an ill-defined aggregate of solitary heads...... 61. Lasianthaea 127.' Pappus wanting or rudimentary, not of scales or awns. 130. Plants scapose or creeping; leaves basally narrowed or sessile; receptacle flat or convex. 131. Ray florets yellow; outer involucral bracts with whitish or yellowish margins; achene apex glandular ...... 78. Chrysanthellum 131.' Ray florets not yellow; outer involucral bracts without whitish margins; achene with a glandular apical peg ...... 38. Lagenifera 130.' Plants erect; leaves petiolate, basally obtuse or truncate; receptacle hemispherical ...... 93. Chrysanthemum 99.' Heads discoid; florets all alike, all tubular, all perfect; corolla equally 4-5-lobed or with 1 deep sinus and thus zygomorphic. 132. Involucre cylindrical of numerous, valvate, slightly connate bracts in one series; leaves often saliently toothed; pappus of fine, weak, white, silky bristles ...... 94. Emilia 132.' Involucre mostly campanulate to funnelform of overlapping, marginally free bracts in several graded series; leaves serrate to entire; pappus various but not as above. 133. Paleas present; achenes mostly compressed (not in Neurolaena). 134. Leaves 3-nerved from near the base; herbs. 135. Leaves eglandular; pappus of minute scales ...... 60. Garcilassa 135.' Leaves glandular beneath; pappus of strigose awns ...... 59. E leutheranthera 134.' Leaves 1-nerved; shrubs or vines. 136. Achenes prominently winged ...... 72. Verbesina 136.' Achenes unwinged. 137. Leaves glabrous above; herbs less than 80 cm tall; heads sessile, solitary, or paired on a leafy rhachis; pappus of stout awns ...... 83. Trichospira 137.' Leaves pubescent above; herbs or shrubs over 80 cm tall; heads in open, pedunculate, many-sided inflorescences; pappus of strigulose bristles. 138. Leaves with numerous, minute glands beneath; heads bisexual; verrucose hairs present ...... 97. Neurolaena 138.' Leaves eglandular; heads functionally unisexual; verrucose hairs wanting ...... 33. Archibaccharis 133.' Paleas wanting; achenes various. 139. Heads united into glomerules in a common involucre of indurate bracts, this sometimes subtended by foliaceous bracts as well, the glomerules mostly appearing as sessile fascicles; herbs. 140. Leaves mostly basal on the lower one half of the stem, the ]ower surfaces with long, stout hairs; glomerules on mostly leafless peduncles with outer bracts (leaves) appressed to the glomerules, glomerules wanting on upper leaves. 141. Glomerules sessile on an elongate spike; glomerules narrow, ellipsoidal ...... 7. Pseudelephantopus 141.' Glomerules mostly terminal, a few sessile ones present; glomerules as broad as tall, globose, or campanulate ...... 6. E lephantopus 140.' Leaves mostly cauline, the lower surfaces whitish-lanate beneath the long hairs; glomerules mostly on leafy stems, the outer bracts (leaves) foliaceous, not appressed to the glomerule. 142. Involucral bracts glabrous or with a few long hairs; heads narrow, ellipsoidal ...... 8. Rolandra 142.' Involucral bracts pilose; heads oblong ...... 9. Spiracantha 139.' Heads all distinct, not in a common involucre, if appearing in a sessile fascicle, the heads distinct; herbs, vines, or shrubs. 143. Heads on elongate peduncles, subtended by serrate subinvolucral bracts resembling the leaves (glandular-punctate) ...... 1. Centratherum 143.' Heads sessile or nearly so, bracts, when present, subentire. 144. Heads in sessile glomerules on leafy or leafless branches. 145. Leaves narrow, chartaceous, basally narrowed; herbs; pappus of low, connate scales ...... 4. Struchium 145.' Leaves broad, coriaceous, basally rounded; woody vines; pappus of strigose bristles (awns) ...... 2. Piptocarpha 144.' Heads individually sessile or pedicellate but not in sessile glomerules. 146. Achenes with a few, flat, elongate, awnlike, twisted, strap- like bristles; head with few (to 6) florets ...... 3. Pollalesta 146.' Achenes with many strigose bristles and sometimes short hairs or scales; heads mostly with many florets. 147. Leaves often with pointed lobes; style branches glabrate, lacking conspicuous hairs; achenes glabrate towards the base, eglandular. 148. Involucral bracts drying with prominent, contrasting veins, eglandular; leaves 1-nerved ...... 97. Neurolaena 148.' Involucral bracts with obscure venation, minutely glandular; leaves 3-5-nerved from a point well above the base ...... 20. Decachaeta 147.' Leaves unlobed or the lobes rounded; style branches pilose; achenes pilose or hispid, sometimes glandular ...... 5. Vernonia
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