(Last Modified On 5/23/2024)
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Acceptance
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Accepted
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(Last Modified On 8/13/2009)
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POACEAE (GRAMINEAE) (Grass Family)
Plants annual or perennial, herbaceous or sometimes woody,
sometimes with rhizomes, stolons, corms, bulbs, and/or tuberous thickenings,
monoecious, dioecious, or more commonly with perfect flowers. Aerial stems
circular or less commonly somewhat flattened, jointed at the nodes and often
hollow between them. Leaves basal and/or alternate, usually noticeably 2‑ranked,
“grasslike” (usually linear), parallel‑veined, the bases strongly
sheathing, the sheaths open or less commonly closed (fused around the stem all
or most of the way to the summit), usually with a scalelike or hairy ligule on
the inner (upper) surface at the tip (summit), the leaf blades sometimes
lacking or highly reduced. Inflorescences with the basic units spikelets,
these 1 to many, terminal and often also axillary, arranged into spikes,
racemes, panicles, or variations of these types, usually composed of 2 basal,
sterile bracts, the lower (first) and upper (second) glumes,
and 1 to many individual florets (flowers) arranged in alternate, 2‑ranked
fashion (rarely appearing spirally arranged elsewhere) along a short rachilla
(spikelet axis). Florets usually consisting of an outer bract (with regard to
the rachilla), the lemma; and an inner bract (with regard to the
rachilla), the palea; these facing each other and subtending the
staminate and/or pistillate portions of the floret. Perianth reduced to 2(3) lodicules
(minute, fleshy scales) located around the base of the ovary and/or stamens,
rarely absent. Stamens 1, 2, 3, or 6, but usually 3 (–120 elsewhere). Pistil 1,
structurally with 3 fused carpels, but functionally with 1 carpel containing 1
ovule. Styles 2 or less commonly 1, 3, or absent. Stigmas 2 or less commonly 3.
Fruits specialized achenes known as caryopses or grains (differing from
standard achenes in that the fruit wall [pericarp] is fused to the seed coat),
except in some species of the tribe Eragrostideae, which have achenes. Six
hundred to 650 genera, about 10,000 species, worldwide.
The Poaceae are a large and complex family with many unusual
floral and vegetative structures that require an extensive, specialized
terminology. Many of these structures are illustrated in Plate 119. Readers
wishing to learn more details of grass morphology and anatomy should consult
any of several good references available on the family, notably Gould and Shaw
(1983) and Clark and Pohl (1996).
Grasses are extremely important economically and have been
cited as a critical factor in the development of human civilization. Grain
crops, such as rice (Oryza sativa), wheat (Triticum aestivum),
corn (Zea mays), barley (Hordeum vulgare), rye (Secale
cereale), oats (Avena fatua var. sativa), sorghum (Sorghum
bicolor), and various millets (several species of Echinochloa, Panicum,
Pennisetum, and Setaria, among others) are major sources of food for
both humans and livestock. Sugar cane (Saccharum officinarum) is a
principal source of sugar. Other species, including several bamboos, also are
eaten. Numerous native and introduced species are grazed by livestock in
pastures or open ranges and as hay. The Poaceae also provide structural
materials for buildings, furniture, fences, baskets, and numerous implements,
ranging from chopsticks to fishing poles. Grasses are important in erosion
control, soil conservation, land reclamation (following mining or other
disasters), and as turf for lawns and golf courses. A variety of species are
cultivated as ornamentals. On the negative side, a number of species are
commercially important weeds. The family, which consists almost entirely of
wind‑pollinated species, also contributes heavily to hay fever problems,
although a relatively small number of genera produce most of the allergenic
pollen.
Although only the fifth largest family of flowering plants
in terms of number of species (ranking behind the Asteraceae, Orchidaceae,
Fabaceae, and Rubiaceae worldwide, but second only to the Asteraceae in
Missouri), the Poaceae probably are the most abundant angiosperm family in the
world in terms of number of individuals and land coverage. Therefore, the
family is extremely important ecologically. Grasses are major components of
nearly all global vegetation types and contribute significantly to the total
net photosynthesis and production of biomass worldwide. They interact
ecologically and/or physiologically with a huge number of different plants,
fungi, insects, birds, mammals, and other fauna. Herbivores and in particular
seed eaters rely heavily on grasses for food. These include most North American
game mammals, as well as songbirds and migratory waterfowl. Other animals,
particularly some insects, require grasses as a substrate for laying eggs and a
larval food source to complete their life cycles. A number of symbiotic and
parasitic viruses, bacteria, fungi, and animals similarly have obligate
relationships with grasses. Grasses also provide shelter and hiding places from
predators for many small animals.
Physiologically, grasses have been divided into two groups,
based upon variations in photosynthesis that correlate with certain anatomical
features (for reviews, see Brown, 1977; Campbell, 1985; Clayton and Renvoize,
1986; or most textbooks in plant anatomy, physiology, or taxonomy). The
“normal” photosynthetic pathway is predominate in angiosperms and is known as
the C3 pathway. Globally, it characterizes species of the
subfamilies Bambusoideae sensu lato, Centothecoideae, and Pooideae, as well as
about 90 percent of the Arundinoideae, about 20 percent of the Panicoideae, and
two genera of the Chloridoideae (for details of classification, see below).
Such species are commonly classified as “cool‑season grasses.” They tend
to be more common in cooler or wetter climates, and the Missouri species tend
to flower in the spring and produce the majority of vegetative growth from the
fall to the spring, with a period of dormancy during the hotter portion of the
growing season and sometimes a short period of dormancy during the coldest
portion of the winter. Many common forest species and some prairie grasses,
particularly those found in the Glaciated Plains Division, are cool‑season
grasses.
The C4 pathway has developed independently in
more than 20 angiosperm families, presumably in response to high‑light
conditions and/or hotter, drier climates. It characterizes nearly all species
of the subfamily Chloridoideae, as well as about 10 percent of the
Arundinoideae and about 80 percent of the Panicoideae. Grasses with C4
physiology have a series of anatomical features centered on details of the
sheath surrounding the vascular bundles (veins) of the leaves that are known
collectively as the Kranz syndrome (a discussion of these details is beyond the
scope of the present volume). The physiological and anatomical specializations
of such species allow them to photosynthesize more efficiently in conditions of
high light and low soil‑moisture, and they have been classified as “warm‑season
grasses.” In Missouri, warm‑season grasses usually produce vegetative
growth throughout the growing season, tend to flower during the summer months,
and have a period of dormancy during the winter months. Many common species of
glades and prairies are warm‑season grasses.
Classification within the Poaceae is complex and
relationships among some genera still are not completely understood. Traditionally,
the family was split into two subfamilies, with varying numbers of tribes.
Following a large number of morphological, anatomical, cytological,
embryological, and phytochemical studies (and most recently molecular‑based
research), most agrostologists (grass specialists) now divide the family into
five to eight subfamilies, each of which can be divided further into a number
of tribes. These subfamilies are the Arundinoideae, Bambusoideae (sometimes
split into three subfamilies), Centothecoideae (sometimes considered part of
the Arundinoideae), Chloridoideae, Panicoideae, and Pooideae. The
classification adopted in the present volume is based upon the summary work of
Clayton and Renvoize (1986), who recognized 6 subfamilies and 40 tribes
worldwide, of which 17 tribes in all 6 subfamilies are represented by native
and introduced species in Missouri. In the treatment below, the genera are
arranged alphabetically in each tribe and the tribes are presented
alphabetically, without regard to subfamily. See Campbell (1985) and Clayton
and Renvoize (1986) for attempts to provide technical keys to subfamilies and
tribes of grasses.
Determination of genus and species for a specimen in this
family requires patience and detailed observations using a hand lens or dissecting
microscope. Relatively subtle characters of spikelet or ligule morphology may
be important for determinations. The components of mature spikelets need to be
studied carefully, as sterile florets may exist and/or some structures, such as
the lowermost glume or the palea of a sterile floret, may be absent or highly
reduced in some species. Collectors should note that rootstocks and mature
fruits often are necessary for accurate determinations. Although several keys
have been published to distinguish grasses based exclusively on vegetative
characters, in practice this can be very difficult, and vegetative specimens
should be avoided. The determination of annual vs. perennial growth form is
important for keying plants of most genera of grasses, but it can be difficult
to establish for some plants. In general, annual species have “soft bases” that
usually can be pulled from the ground with their roots relatively intact, and
they show no evidence of rhizomes, tuberous root thickenings, or previous
years’ stem or leaf bases. Perennials have “hard bases” that are frequently
(but not always) difficult to pull up with intact rootstocks, often have
rhizomes, tuberous roots, or otherwise thickened rootstocks, and usually have
remnants of previous years’ stem and/or leaf bases.
The key to tribes below is adapted from the excellent key of
Gould (1975) and also incorporates elements from Gleason and Cronquist (1991).
The couplets are based on characters that traditionally have been found in keys
to grass genera, and references to microscopic structures are minimized. As a
result the key is quite lengthy, and several of the tribes, notably the
morphologically diverse Aveneae, Eragrostideae, and Poeae, key out in a number
of different places. This is unavoidable, as the technical characters that
define the tribes are not amenable to inclusion in a practical key.
1
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Plants woody or with the aerial stems perennial, not dying back to the ground each winter, usually well branched at maturity with side branches smaller than the main stems; new growth in the spring developing at the nodes of existing stems (in addition to new aerial stems from rhizomes); leaf blades tapering to a short, petiole-like base, jointed to the sheath (Arundinaria)
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5 Bambuseae
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+
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Plants herbaceous, annual or perennial, the aerial stems dying back to the ground each winter; if aerial stems appear stout and woody during growing season, then these unbranched or rarely few-branched; if perennial, new growth in the spring developing from below-ground portions of plants; leaf blades sessile on the sheaths, usually not jointed
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(2)
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2 (1)
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Spikelets appearing as hardened or spiny, burlike clusters, the component structures requiring dissection of the cluster to be observed
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(3)
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+
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Spikelets not hidden in burlike clusters
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(4)
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3 (2)
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Burlike clusters lacking spines, consisting of 3–5 closely aggregated spikelets, the outer covering formed from enlarged, hard and bony upper glumes; plants perennial, with numerous stolons (Buchloe)
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9 Cynodonteae
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+
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Burlike clusters spiny, consisting of 1–3 spikelets enclosed in an involucre of fused bristles; plants annual, tufted (Cenchrus)
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14 Paniceae
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4 (2)
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Spikelets with most of the florets replaced by vegetative bulblets with elongate, linear, pointed tips
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(5)
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+
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Spikelets all or mostly “normal,” none of them replaced by vegetative bulblets (rarely some or all of the spikelets in an otherwise normal inflorescence of most species may be parasitized by fungi or insect larvae, causing abnormal spikelet development)
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(6)
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5 (4)
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Inflorescences of several spikelike racemes, these arranged digitately at the tip of the main inflorescence axis or nearly so (Digitaria)
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14 Paniceae
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+
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Inflorescences highly branched panicles
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15 Poeae
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6 (4)
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Plants dioecious or monoecious, the staminate and pistillate spikelets located on different plants or in different positions on the same plant
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(7)
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+
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Plants with all or many of the spikelets containing 1 or more perfect florets (staminate or rudimentary sterile spikelets also may be present)
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(10)
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7 (6)
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Plants dioecious, low plants, widely creeping but with the flowering stems or branches less than 20 cm tall
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(8)
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+
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Plants monoecious; tall plants with the flowering stems 70–300 cm or more long
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(9)
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8 (7)
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Staminate spikelets with 2 florets; pistillate spikelets with 1 fertile floret, aggregated into ball-shaped, burlike clusters (Buchloe)
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9 Cynodonteae
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+
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Staminate and pistillate spikelets with 4 to many florets, not aggregated into burlike clusters
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11 Eragrostideae
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9 (7)
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Staminate and pistillate inflorescences separate on different parts of the plant or the inflorescences consisting of a short axis with 1–5 dense spikes, each staminate toward the tip and pistillate toward the base
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1 Andropogoneae
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+
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Staminate and pistillate spikelets in the same inflorescence; inflorescences many-branched panicles
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13 Oryzeae
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10 (6)
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Spikelets closely appressed to (appearing sunken into) concave portions of the axis, the inflorescence appearing as an uninterrupted cylinder (this circular in cross-section or appearing somewhat flattened)
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(11)
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+
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Spikelets not appressed to or appearing sunken into a modified axis, the inflorescence various but not appearing as an uninterrupted cylinder
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(13)
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11 (10)
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Lemmas with short to long awns
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17 Triticeae
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+
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Lemmas lacking awns
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(12)
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12 (11)
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Lemma membranous, thinner in texture than the somewhat thickened glumes; spikes not flattened
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1 Andropogoneae
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+
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Lemma of the perfect floret somewhat leathery, thicker in texture than the papery glumes; spikes appearing somewhat flattened
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14 Paniceae
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13 (10)
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Spikelets all or nearly all with only 1 perfect floret (check for stigmas and/or fruits), sometimes also with sterile or staminate floret(s) above or below the perfect floret (note that in the Eragrostideae, occasional spikelets with 2 perfect florets occur within inflorescences that otherwise contain mostly 1-flowered spikelets)
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(14)
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+
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Spikelets all or nearly all with 2 or more perfect florets, sometimes also with additional staminate or sterile florets (note that totally sterile spikelets rarely may be intermingled with the fertile ones)
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(40)
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14 (13)
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Spikelets with 1 or 2 staminate or sterile florets positioned above or below the perfect floret (note that in some species the lower glume may be relatively short or may appear cup-shaped; care must be taken not to confuse the lemma of the staminate or sterile, lower floret(s) with a glume)
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(15)
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+
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Spikelets with only the perfect floret present, without additional staminate or sterile florets
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(20)
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15 (14)
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Spikelets with 1 staminate floret positioned above the perfect floret
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(16)
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+
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Spikelets with 1 or 2 staminate or sterile florets positioned below the perfect floret
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(17)
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16 (15)
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Inflorescences relatively dense panicles, the branches usually rebranched 1 to several times, not spikelike
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4 Aveneae
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+
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Inflorescences consisting of 1 to more commonly several to many, 1-sided, spikelike racemes, these arranged pinnately along the main axis or palmately at its tip
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9 Cynodonteae
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17 (15)
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Lemma of staminate or sterile floret similar in size and texture to the upper glume (or only glume)
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14 Paniceae
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+
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Lemma of staminate or sterile floret different in length and usually also texture from the upper glume (or the glumes absent)
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(18)
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18 (17)
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Glumes absent or reduced to a minute cuplike structure at the spikelet base
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13 Oryzeae
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+
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Glumes well developed, as long as or longer than the lemmas
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(19)
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19 (18)
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Spikelets not flattened or slightly flattened dorsally, the glumes rounded on the back; spikelets usually occurring in pairs of 1 perfect and often nearly sessile, the other staminate or sterile and longer stalked (this sometimes reduced to a hairy stalk); inflorescences consisting of 1 or more spikelike racemes, sometimes with long, silky hairs
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1 Andropogoneae
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+
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Spikelets strongly flattened laterally, the glumes keeled; spikelets not paired along the axis, all similar and perfect; inflorescences panicles, the branches not consisting of spikes or spikelike racemes, mostly rebranched 1 or more times, never with long, silky hairs
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4 Aveneae
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20 (14)
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Lemmas with 3 awns at the tip, these sometimes united into a column near the base, the lateral awns sometimes much shorter than the central awn (Aristida)
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2 Aristideae
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+
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Lemmas awnless or with a single awn, rarely with a pair of narrow teeth on either side of the awn (the awn is sometimes reduced to a small, flattened, 3-lobed appendage in Hordeum)
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(21)
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21 (20)
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Inflorescences dense to open panicles, the branches not spikelike, often rebranched, but sometimes relatively short and appressed to the main axis
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(22)
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+
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Inflorescences consisting of a single terminal spike or raceme or panicles with the main branches consisting of 1-sided spikes or spikelike racemes
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(31)
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22 (21)
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Glumes absent or reduced to a minute cuplike structure at the spikelet base
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13 Oryzeae
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+
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One or both glumes relatively well developed, not cuplike
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(23)
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23 (22)
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Lemma awnless or less commonly with a minute point or short awn at the tip less than 0.5 mm long
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(24)
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+
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Lemma with an awn 1 mm long or usually longer
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(28)
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24 (23)
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Lemma hardened (usually bonelike at maturity), conspicuously thicker in texture than the glumes (note that in these species the fertile floret is subtended by a sterile or staminate floret, but because only 1 glume is present, the sterile floret may be mistaken for an upper glume)
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14 Paniceae
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+
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Lemma membranous or papery, not conspicuously thicker in texture than the glumes
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(25)
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25 (24)
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Ligule a line or band of hairs, sometimes fused into a short membrane at the base
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11 Eragrostideae
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+
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Ligule a membrane, sometimes short or with an uneven margin, but not densely hairy along the margin
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(26)
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26 (25)
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Ligule 3–11 mm long; stamen 1 per floret; spikelets disarticulating below the glumes, strongly flattened, the lemmas keeled on the back
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4 Aveneae
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+
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Ligule 0.3–1.5 mm long; stamens 3 per floret; spikelets disarticulating above the glumes, only slightly flattened, the lemmas rounded on the back
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(27)
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27 (26)
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Floret with the palea absent or less than 2/3 as long as the lemma; lemma (3)5-nerved, sometimes faintly so
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4 Aveneae
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+
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Floret with the palea about as long as the lemma; lemma 3-nerved, the lateral nerves sometimes faint
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11 Eragrostideae
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28 (23)
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Lemma with the awn attached along the midnerve behind the tip (sometimes only slightly so)
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4 Aveneae
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+
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Lemma with the awn attached at the tip, often tapered to the awn
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(29)
|
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29 (28)
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Spikelets 1.5–5.0 mm long (excluding the awns)
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11 Eragrostideae
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+
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Spikelets 6.5–45.0 mm long (excluding the awns)
|
(30)
|
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30 (29)
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Glumes less than 1/2 as long as the floret, the lower glume absent or less than 1 mm long (Brachyelytrum)
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6 Brachyelytreae
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+
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Glumes as long as or usually longer than the floret (excluding the awns), both well developed and more than 5 mm long
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16 Stipeae
|
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31 (21)
|
Inflorescences panicles with the main branches consisting of 1-sided spikes or spikelike racemes
|
(32)
|
+
|
Inflorescences consisting of a single spike or raceme at the tip of the main stem and sometimes also of leafy, lateral branches
|
(33)
|
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32 (31)
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Lemma hardened (usually bonelike at maturity), conspicuously thicker in texture than the glumes (note that in these species the fertile floret is subtended by a sterile or staminate floret, but because only 1 glume is present, the sterile floret may be mistaken for an upper glume)
|
14 Paniceae
|
+
|
Lemma membranous or papery to somewhat thickened, but not conspicuously thicker in texture than the glumes
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9 Cynodonteae
|
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33 (31)
|
Lemma with an awn 1 mm long or usually longer (this modified into a short, flattened, 3-lobed appendage in some cultivars of Hordeum)
|
(34)
|
+
|
Lemma awnless or less commonly with a minute point or short awn at the tip less than 0.5 mm long
|
(38)
|
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34 (33)
|
Inflorescences with clusters of 3 spikelets positioned on opposite sides of the main axis, the lateral spikelets of each cluster often sterile
|
17 Triticeae
|
+
|
Inflorescences with the spikelets attached singly or along short branches, not positioned on all sides of the main axis, all fertile
|
(35)
|
|
35 (34)
|
Spikelets 1.5–6.0 mm long (excluding the awns)
|
(36)
|
+
|
Spikelets 6.5–45.0 mm long (excluding the awns)
|
(37)
|
|
36 (35)
|
Awn attached at or below the midpoint of the lemma; palea absent; inflorescences appearing as dense, uninterrupted, more or less cylindrical spikes
|
4 Aveneae
|
+
|
Awn attached at the tip of the lemma; palea about as long as the lemma; inflorescences appearing as narrow, irregularly interrupted, spikelike racemes
|
11 Eragrostideae
|
|
37 (35)
|
Glumes less than 1/2 as long as the floret, the lower glume absent or less than 1 mm long
|
6 Brachyelytreae
|
+
|
Glumes as long as or usually longer than the floret (excluding the awns), both well developed and more than 5 mm long
|
16 Stipeae
|
|
38 (33)
|
Glumes noticeably longer than the lemma, oblong, narrowed or rounded abruptly at the tip to an awn, 3-nerved
|
4 Aveneae
|
+
|
Glumes slightly shorter to slightly longer than the lemma, lanceolate to ovate or triangular, narrowed more gradually to the tip, awnless or less commonly tapered to an awn, 1-nerved, or if somewhat oblong and 3-nerved then awnless
|
(39)
|
|
39 (38)
|
Palea absent; glumes 3-nerved; spikelets strongly flattened laterally
|
4 Aveneae
|
+
|
Palea about as long as the lemma; glumes 1(3)-nerved; spikelets only slightly flattened laterally
|
11 Eragrostideae
|
|
40 (13)
|
Inflorescences consisting of 1 or more spikes or spikelike racemes
|
(41)
|
+
|
Inflorescences open or dense panicles, the branches not consisting of spikes or spikelike racemes
|
(53)
|
|
41 (40)
|
Inflorescences panicles with the main branches consisting of 1-sided spikes or spikelike racemes (if rarely appearing as a single spike or spikelike raceme then this appearing lateral and not as a terminal extension of the main stem)
|
(42)
|
+
|
Inflorescences consisting of a single spike or raceme appearing as an extension at the tip of the main stem and sometimes also of leafy, lateral branches
|
(43)
|
|
42 (41)
|
Spikelets in dense, headlike clusters toward the ends of the inflorescence branches, not in 2 definite rows
|
15 Poeae
|
+
|
Spikelets in 2 rows along nearly the entire length of the branches
|
11 Eragrostideae
|
|
43 (41)
|
Ligule a line or band of hairs, often fused into a membrane at the base
|
(44)
|
+
|
Ligule membranous, sometimes with an irregular, but not noticeably hairy margin (sometimes minutely hairy in the Aveneae), rarely absent
|
(45)
|
|
44 (43)
|
Lemmas strongly 3-nerved, awnless
|
11 Eragrostideae
|
+
|
Lemmas faintly 5-nerved, long-awned (awns often absent in axillary spikelets hidden in the leaf sheaths)
|
3 Arundineae
|
|
45 (43)
|
Flowering stems 3–8(–13) cm long, spreading; inflorescences appearing 1-sided, the spikelets attached in 2 rows on 1 side of the axis
|
15 Poeae
|
+
|
Flowering stems more than 20 cm long, or if shorter then erect or ascending (sometimes from spreading bases); inflorescences not appearing 1-sided, the spikelets radiating in all directions or attached on opposite sides of the axis
|
(46)
|
|
46 (45)
|
Spikelets flattened, attached with an edge against the inflorescence axis
|
15 Poeae
|
+
|
Spikelets not flattened, or if flattened then attached with a flat side against the inflorescence axis
|
(47)
|
|
47 (46)
|
Spikelets 2–4 at each node of the inflorescence axis
|
(48)
|
+
|
Spikelets occurring singly at the nodes of the inflorescence axis or singly along short, appressed branches
|
(49)
|
|
48 (47)
|
Inflorescences 1–4 cm long; spikelets paired along short, ascending branches, 1 of each pair sterile and the other with fertile florets (Cynosurus)
|
15 Poeae
|
+
|
Inflorescences 5–40 cm long; spikelets 2–4 per node of the inflorescence axis, all similar and with fertile florets
|
17 Triticeae
|
|
49 (47)
|
Leaf sheaths closed to well above the middle, sometimes to the tip or nearly so
|
7 Bromeae
|
+
|
Leaf sheaths free to the base or nearly so
|
(50)
|
|
50 (49)
|
Inflorescences spikelike panicles (look closely, especially toward the base), the spikelets occurring along short, appressed branches
|
(51)
|
+
|
Inflorescences spikes or racemes, the spikelets attached directly along the main axis
|
(52)
|
|
51 (50)
|
Lemmas faintly 5-nerved
|
4 Aveneae
|
+
|
Lemmas 3-nerved
|
11 Eragrostideae
|
|
52 (50)
|
Stamen 1 per floret; plants relatively delicate and slender annuals, the inflorescences racemes, the spikelets with often short but noticeable stalks
|
15 Poeae
|
+
|
Stamens 3 per floret; plants perennials or relatively robust and stout annuals, the inflorescences spikes, the spikelets sessile or minutely stalked
|
17 Triticeae
|
|
53 (40)
|
Flowering stems relatively stout and tall, 2–6 m long
|
(54)
|
+
|
Flowering stems more slender and shorter, less than 2 m long
|
(55)
|
|
54 (53)
|
Leaf blades rounded or narrowed to a sessile base, not jointed to the sheath; spikelets 10–15 mm long
|
3 Arundineae
|
+
|
Leaf blades tapered abruptly to a short, petiole-like base, jointed to the sheath; spikelets 15–50 mm long
|
5 Bambuseae
|
|
55 (53)
|
Leaf sheaths closed to above the middle, sometimes nearly to the tip
|
(56)
|
+
|
Leaf sheaths open nearly to the base (but the margins sometimes overlapping) or fused only below the midpoint
|
(59)
|
|
56 (55)
|
Inflorescences with relatively few branches, the spikelets numerous in dense, headlike, more or less 1-sided clusters toward the branch tips
|
15 Poeae
|
+
|
Inflorescences usually with several to numerous branches, the spikelets all or mostly stalked, not in dense headlike or 1-sided clusters
|
(57)
|
|
57 (56)
|
Lemmas lacking teeth, rounded or narrowed to an entire or minutely irregular tip, awnless or short-awned
|
(58)
|
+
|
Lemmas tapered or narrowed to 2 minute teeth at the tip, often awned from between the teeth
|
7 Bromeae
|
|
58 (57)
|
Lemmas tapered to a short awn at the tip; leaf blades less than 2 mm wide
|
15 Poeae
|
+
|
Lemmas rounded or narrowed to an awnless tip; leaf blades more than 2 mm wide
|
12 Meliceae
|
|
59 (55)
|
Fruits conspicuously beaked, about as long as and not hidden by the lemma at maturity
|
10 Diarrheneae
|
+
|
Fruits not beaked, much shorter than and mostly hidden by the enfolding lemma
|
(60)
|
|
60 (59)
|
At least some of the lemmas in each spikelet with a short or long awn
|
(61)
|
+
|
Lemmas all awnless
|
(64)
|
|
61 (60)
|
Lemmas with the awn attached along the midnerve behind the tip (sometimes only slightly so)
|
4 Aveneae
|
+
|
Lemmas with the awn attached at the tip (sometimes between 2 minute teeth at the tip)
|
(62)
|
|
62 (61)
|
Glumes as long as or longer than the rest of the spikelet (excluding the awns)
|
3 Arundineae
|
+
|
Glumes noticeably shorter than the rest of the spikelet
|
(63)
|
|
63 (62)
|
Paleas with a conspicuous fringe of long, silky hairs toward the tip; lemmas noticeably 3-nerved
|
11 Eragrostideae
|
+
|
Paleas glabrous, roughened, or sometimes short-hairy along the nerves, but without a fringe of long, silky hairs toward the tip; lemmas mostly 5-nerved, sometimes faintly so (sometimes faintly 3-nerved in Festuca)
|
15 Poeae
|
|
64 (60)
|
One or both glumes longer than the lowermost lemma
|
4 Aveneae
|
+
|
Glumes noticeably shorter than the lowermost lemma
|
(65)
|
|
65 (64)
|
Lemmas 5–15-nerved, sometimes faintly so
|
(66)
|
+
|
Lemmas noticeably 3-nerved
|
(67)
|
|
66 (65)
|
Spikelets strongly flattened, the lowermost 1–3 florets sterile and consisting only of lemmas
|
8 Centotheceae
|
+
|
Spikelets slightly to moderately flattened, the lowermost florets all fertile (look for paleas, stamens, stigmas, and/or fruits)
|
15 Poeae
|
|
67 (65)
|
Ligule a line or band of hairs, sometimes fused into a membrane at the base
|
11 Eragrostideae
|
+
|
Ligule membranous, sometimes with an irregular but not hairy margin
|
15 Poeae
|
|
|