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(Last Modified On 5/31/2013)
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(Last Modified On 5/31/2013)
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Family
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CONVOLVULACEAE
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Contributor
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DANIEL F. AUSTIN
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Description
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Herbs, vines, lianas, shrubs, or trees, the sap milky in some species; the root- stocks sometimes large; sometimes parasitic. Leaves mostly simple, pinnately lobed or pectinate, palmately compound in some species, or reduced to scales in Cuscuta; exstipulate. Inflorescences axillary, dichasial, solitary, racemose, or paniculate. Flowers perfect or imperfect (some African species), regular or slightly zygomorphic, small and inconspicuous to large and showy but mostly evanescent; sepals 5, free, imbricate, equal or unequal, persistent, occasionally accrescent in fruit; corolla sympetalous, tubular, funnelform, campanulate, urceo- late or salverform, the limb with 5 lobes or teeth or almost entire, and with plicae and interplicae, the buds mostly induplicate; stamens 5, distinct, the filaments inserted on the corolla tube base alternate with corolla lobes, the anthers mostly linear or oblong, 2-celled, extrorse; disc annular or cupuliform, sometimes 5-lobed, occasionally absent; ovary superior, of 2 to 4 carpels, usually 2- or 3-locular, each locule biovulate, rarely 4- or 6-loculate or unilocular with 4 ovules, the style filiform, simple or bifid or 2 distinct styles present, the stigma capitate or bilobate or the stigmas 2 and linear, ellipsoid or globose. Fruits 1- to 4-locular, capsular, dehiscent by valves, transversely dehiscent, irregularly dehiscent or indehiscent; seeds 1-4, commonly fewer than ovules, glabrous or pubescent, the endosperm absent or scanty, cartilaginous, the cotyledons mostly foliaceous.
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Habit
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Herbs, vines, lianas, shrubs, or trees
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Distribution
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This worldwide family has numerous species in the tropics, fewer in tem- perate zones; it contains 40 or 50 genera, and 1200 or more species.
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Note
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The type genus is Convolvulus L. There is little agreement on generic delimitation, the family being largely natural. Three families have been segregated, however. The monotypic Humbertiaceae was segregated by Pichon (1951), but studies of other primitive elements in the family suggest that it is best included in the Con- volvulaceae (Austin, 1973a). The Dichondraceae is apparently a sequential evolutionary phylad most closely allied with the tribe Poraneae, and it is also best included in the Convolvulaceae. The Cuscutaceae, apparently derived from the Dichondraceae or a common ancestor, has many unique characteristics, and most modern angiosperm phylogenists recognize it as a separate family. While there is considerable justification for this separation, its closest allies lie within the Convolvulaceae and the genus will be included for this treatment. Several members of the family are of economic value. Ipomoea batatas, the sweet potato, is an important food plant throughout the world. Of lesser eco- nomic importance are the species cultivated for their flowers, e.g. Argyreia ner- vosa (Burm. f.) Boj., Ipomoea (Calonyction) alba L., Ipomoea carnea Jacq., Ipomoea (Quamoclit pennata (Desr.) Boj.) quamoclit L., Ipomoea tricolor Cav., Porana paniculata Roxb., and Stictocardia campanulata (L.) Merrill. Pollen characteristics have classically been used as important criteria for generic delimitation in the family. It is difficult or impossible to distinguish Merremia, Operculina, and Ipomoea without resorting to pollen. The first two genera have smooth pollen; Ipomoea has spinulose grains. The differences are fairly easily seen with a dissecting microscope. This obscure pollen character- istic and the necessity for fruiting material to separate Merremia and Operculina led Shinners (1970) to lump these into Ipomoea in his last publication on the Convolvulaceae before his untimely death. Hallier (1893) divided the family by using pollen characteristics as major criteria. While there is no doubt that pollen is an important criterion for under- standing phyletic relationships, there is no reason why it should be weighted in such a heavy manner. Present knowledge of the family suggests re-examination of Hallier's tribal arrangements. I have discussed this elsewhere (Austin 1973a) and will basically follow my previous tribal arrangement. The following synoptic key indicates tribal separations. The artificial key should be used to identify Panamanian plants.
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Reference
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Austin, D. F. The American Erycibeae (Convolvulaceae); Maripa, Dicrano- styles, and Lysiostyles-I. Systematics. Ann. Missouri Bot. Gard. 60: 306-412. 1973a [1974]. Austin, D. F. The American Erycibeae (Convolvulaceae). Maripa, Dicranostyjles, and Lysiostyles-JJ. Palynology. Pollen & Spores 15: 203-226. 1973b. Hallier, H. Versuch einer natiirlichen Gliederung der Convolvulaceen auf morphologischer und anatomischer Grundlage. Bot. Jahrb. (Syst.) 16: 453-591. 1893. Pichon, M. Le fruit et la graine des Humbertiacees. Bull. Soc. Bot. France 98: 235-237. 1951. Shinners, L. H. Convolvulaceae. Pp. 1241-1261, in D. S. Correll & M. C. Johnston, "Manual of the Vascular plants of Texas." 1970. Verdcourt, B. Convolvulaceae. In C. E. Hubbard & E. Milne-Redhead, "Flora of Tropical East Africa." 1963.
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Key
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SYNOPTIC KEY TO TRIBES a. Leaves absent or scale-like; plants without chlorophyll and usually yellowish or orange; styles usually 2 and distinct, occasionally connate basally; fruits capsular, opening either by circumscissile dehiscence or irregularly; cotyledons absent...... Tribe 8. Cuscuteae (Cuscuta) aa. Leaves present and fully formed although variable; plants with chlorophyll; styles mostly 1 or rarely 2, distinct or connate basally; fruits capsular and dehiscent or bac- cate or nut-like; cotyledons present. b. Prostrate herbs, to 1 m long; flowers mostly solitary in leaf axils; calyx connate basally, deeply 5-lobed; fruits deeply 2-lobed or almost 2 and separate, utricu- late ...... Tribe 7. Dichondreae (Dichondra) bb. Twining, diffuse, or erect vines, herbs or lianas, mostly over 1 m long if twining, usually smaller if erect or diffuse (prostrate in Evolvulus nummularius); flowers solitary to paniculate; calyx lobes free; fruits entire, capsular to operculate or indehiscent. c. Fruits indehiscent, nut-like to baccate; large lianas and woody vines; flowers white, lavender to scarlet. d. Leaves elliptic, coriaceous to chartaceous, glabrous to glabrate; flowers campanulate-funnnelform, lavender to white-lavender; fruits nut-like; em- bryos with non-plicate fleshy cotyledons - Tribe 1. Erycibeae (Maripa) dd. Leaves ovate-cordate, chartaceous to membranaceous, glabrous to densely pubescent below; flowers mostly funnelform, rarely campanulate-funnelform, scarlet, lavender or white; fruits baccate and 4-seeded or chartaceous and 1-seeded; embryos with foliaceous plicate cotyledons ...... Tribe 6. Argyreieae (Argyreia, Stictocardia, Turbina) cc. Fruits dehiscent, capsular to operculate (indehiscent in Iseia); twining vines, suffrutescent shrubs, herbs or woody vines; flowers white, yellow, orange, pink, red or lavender. e. Flowers mostly smaller than 2 cm across, broadly campanulate to subrotate, white or blue; small vines or diffuse to suberect suffrutescent herbs, mostly herbaceous ...... Tribe 3. Convolvuleae (Evolvulus, Jacquemontia) ee. Flowers mostly larger than 2 cm across, broadly campanulate, funnelform or salverform, white, yellow, orange, pink, red or lavender; medium to large vines, herbaceous to woody, rarely large erect to scrambling shrubs. f. Corolla interplicae densely pubescent, corollas white, funnelform to sub- campanulate; styles bipartite or 2 (one in Iseia); fruits capsular (Bon- amia) or indehiscent (Iseia) ...... Tribe 2. Cresseae (Bonamia, Iseia) ff. Corolla interplicae glabrous or with inconspicuous indument, corollas mostly colored, sometimes white, campanulate, funnelform or salverform; style one; fruits capsular to operculate. g. Corollas yellow or white and campanulate, if pink then salverform; stamens often spirally twisted at anthesis; pollen 3-colpate or panto- colpate ...... Tribe 4. "Merremioids" (Aniseia, Merremia, Operculina) gg. Corollas red, orange, pink, lavender or purple, if white then salver- form, mostly funnnelform or salverform; stamens rarely spirally twisted at anthesis, usually straight; pollen pantoporate and spinulose ...... Tribe 5. Ipom oeeae (Ipomoea) ARTIFICIAL KEY TO GENERA a. Plants parasitic; stems yellow to orange, without chlorophyll; leaves reduced to scales ...... 14. Cuscuta aa. Plants not parasitic; stems green or brownish, chlorophyllous; leaves normally developed. b. Flowers to 5 mm across; ovary and fruit deeply biolobate or carpels distinct; leaves reniform; small repent herbs ...... 13. Dichondra bb. Flowers more than 5 mm across; ovary and fruit entire; leaves various, rarely reni- form; if repent herbs, not small. c. Fruits indehiscent, subbaccate to dry. d. Leaves basally cordate to subcordate. e. Sepals enveloping the fruit; flowers scarlet ...... 11. Stictocardia ee. Sepals reflexed in fruit; flowers white or purple. f. Corolla white or lavender, often dark inside at base; fruits with en- larged sepals, dry; seeds mostly one, glabrous to puberulent ...... 12. Turbina ff. Corolla purple, darker inside; fruits without enlarged sepals, sub- baccate; seeds 1-4, glabrous ...... 10. Argyreia dd. Leaves basally obtuse to acute. g. Corolla white; fruits bilocular with spongy mesocarp; seeds 4, peri- sperm absent; herbaceous vines ...... 3. Iseia gg. Corolla lavender to purple; fruits incompletely bilocular without meso- carp; seeds 1(-4), perisperm present; woody lianas ...... 1. Maripa cc. Fruits dehiscent, dry; mostly herbs, less commonly woody vines. h. Style one and bifid, or styles 2 and distinct. i. Lianas; style one, bifid; stigmas capitate ...... 2. Bonamia ii. Herbs or small suffrutescent shrubs, not scandent; styles 2; stigmas elongate, bifid ...... 5. Evolvillus hh. Style one, entire. j. Sepals unequal, the outer larger and concealing the inner ...... 8. Aniseia jj. Sepals equal to subequal. k. Stigmas ellipsoid to oblong ...... 4. Jacquemontia kk. Stigmas globose to bi-globose. 1. Pollen smooth; 3-colpate to polycolpate. m. Capsule transversely dehiscent ...... 7. Operculina mm. Capsule longitudinally or irregularly dehiscent ...... 6. Merremia 11. Pollen spinulose; pantoporate ...... 9. Ipomoea
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