POACEAE
5
Keys to tribes
Key 1
1a. Bamboos, culms woody; lower culm sheaths broad with rudimentary blades ................................................... 1. Bambuseae (p. 7)
1b. Herbs, occasionally reeds or culms canelike; lower culm sheaths with normal blades.
2a. Spikelets arranged in pairs (rarely triads) on fragile racemes; raceme rachis breaking up into segments bearing a
sessile and pedicelled spikelet .............................................................................................................................................. Key 2
2b. Spikelets arranged singly in panicles or racemes (occasionally raceme fragile but spikelets single; or spikelets
paired but raceme tough).
3a. Spikelets with strictly 2 florets and no rachilla extension; lower floret staminate or barren, sometimes reduced
to an empty lemma, upper floret fertile ......................................................................................................................... Key 2
3b. Spikelets with 1 to many florets (if 2 florets, then both fertile, or the lower fertile, or rachilla extension
present).
4a. Spikelets with 2 or more fertile florets .................................................................................................................... Key 3
4b. Spikelets with 1 fertile floret, sometimes with additional staminate or barren florets ........................................... Key 4
Key 2
1a. Spikelets disarticulating at maturity above glumes.
2a. Spikelets disarticulating above glumes; lemmas both orbicular to broadly elliptic, awnless; leaf blades
lanceolate to ovate ..................................................................................................................................... 25. Isachneae (p. 554)
2b. Spikelets disarticulating below fertile (upper) floret; lower lemma resembling upper glume,
persistent, upper lemma terete, often awned; leaf blades linear ......................................................... 27. Arundinelleae (p. 561)
1b. Spikelets falling entire at maturity, either singly or with other spikelets and inflorescence parts attached.
3a. Spikelets single, or if paired both spikelets alike; glumes thinner than fertile floret, lower glume
short or even suppressed; fertile floret papery to crustaceous or leathery, awnless .................................. 24. Paniceae (p. 499)
3b. Spikelets paired, usually one sessile and the other pedicelled, often dissimilar and arranged in fragile
racemes; glumes as long as spikelet, tougher than and enclosing hyaline florets; fertile floret often
with geniculate awn (spikelets rarely single or both pedicelled, but then either in fragile racemes
or geniculately awned) ...................................................................................................................... 28. Andropogoneae (p. 570)
Key 3
1a. Inflorescence of one or more racemes.
2a. Ligule a line of hairs; lemmas 1–3-veined ......................................................................................... 22. Eragrostideae (p. 457)
2b. Ligule membranous; lemmas 5 or more veined.
3a. Leaf sheaths tubular, margins joined for most or all of length ............................................................... 9. Meliceae (p. 212)
3b. Leaf sheaths not tubular, margins free.
4a. Spikelets placed broadside to rachis; both glumes present; ovary with hairy apical appendage.
5a. Spikelets shortly pedicellate, usually terete or almost so; lemmas 7–9-veined ............ 13. Brachypodieae (p. 368)
5b. Spikelets sessile, laterally compressed (if rarely pedicellate, lemmas 5-veined) ................... 15. Triticeae (p. 386)
4b. Spikelets placed edgeways to rachis; lower glume absent (except terminal spikelet);
ovary glabrous ................................................................................................................. 11. Poeae (61. Lolium: p. 243)
1b. Inflorescence a panicle, open, contracted, or dense and spikelike.
6a. Spikelets with 2 florets, rachilla extension absent; one or both florets usually indurated.
7a. Lemmas entire, awnless, glabrous or puberulous ............................................................................... 25. Isachneae (p. 554)
7b. Lemmas 2-toothed, awned from sinus, densely hispid .................................................................... 26. Eriachneae (p. 561)
6b. Spikelets with several florets, or if 2 then rachilla extension present.
8a. Lemmas deeply cleft into 7–9 awns ............................................................................................ 21. Pappophoreae (p. 456)
8b. Lemmas awnless or 1-awned.
9a. Leaf sheaths tubular, the margins joined for most or all of length .................................................. 9. Meliceae (p. 212)
9b. Leaf sheaths not tubular, margins free.
10a. Culms reedlike, usually tall; panicle large, plumose ........................................................ 18. Arundineae (p. 447)
10b. Culms mostly slender, if tall then not reedlike; panicle not large and plumose (if plant
a large tussock with serrate leaf blades and plumose panicle, see 113. Cortaderia).
11a. Ligule a line of hairs.
12a. Basal internodes swollen; leaf blades articulated with sheath
................................................................................................. 18. Arundineae (114. Molinia: p. 447)
12b. Basal internodes not swollen; leaf blades persistent ................................. 22. Eragrostideae (p. 457)
11b. Ligule membranous.
13a. Pericarp thickened into a pale beak or knob at grain apex .......................... 10. Diarrheneae (p. 223)
13b. Pericarp not thickened.
14a. Leaf blades with obvious cross veins, broad .................................... 16. Centotheceae (p. 444)
POACEAE
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14b. Leaf blades without cross veins.
15a. Lemmas 3-veined; spikelets in dense globular
clusters on an elongate axis ......................... 18. Arundineae (118. Elytrophorus: p. 450)
15b. Lemmas 5 or more veined; spikelets not in
globular clusters.
16a. Glumes usually as long as spikelet, always
longer than lowest lemma.
17a. Ligule a line of hairs; awn, when present, arising
from sinus of 2-lobed apex ..................................... 19. Danthonieae (p. 449)
17b. Ligule membranous; awn, when present, arising
from lemma back ............................................................ 12. Aveneae (p. 316)
16b. Glumes shorter than spikelet, usually shorter than lowest lemma;
lemmas awnless or a straight awn arising at or near apex.
18a. Ovary glabrous or hairy, styles arising from its apex; lemmas
awnless or awned from apex (awn rarely subapical, but
then leaf sheaths glabrous and palea keels scabrid) ......... 11. Poeae (p. 224)
18b. Ovary with a hairy apical appendage, styles arising beneath
it; lemmas awned from just below apex; leaf sheaths
hairy; palea keels ciliate ................................................ 14. Bromeae (p. 370)
Key 4
1a. Glumes absent or both very short.
2a. Spikelets in umbellate clusters; dwarf ephemeral ............................................................. 12. Aveneae (85. Coleanthus: p. 340)
2b. Spikelets in a panicle; annual or perennial.
3a. Palea 3–7-veined, 1-keeled; anthers often 6; caryopsis not beaked ........................................................ 4. Oryzeae (p. 181)
3b. Palea 2-veined, convolute; anthers 2; caryopsis beaked .............................................................. 5. Brachyelytreae (p. 187)
1b. Glumes well developed, at least the upper.
4a. Spikelets unisexual; female spikelet inflated, shell- or urn-shaped ............................................................... 2. Phareae (p. 180)
4b. Spikelets bisexual, not shell- or urn-shaped.
5a. Leaf blades with cross veins, broadly linear to ovate.
6a. Pedicel falling with spikelet; spikelets very small, numerous in a large panicle; florets 2;
lower floret sterile, upper floret fertile, its lemma with ciliate margins ............................ 17. Thysanolaeneae (p. 446)
6b. Pedicel persistent; florets 1 or more; lowest floret fertile when more than 1.
7a. Leaf blades broadly linear with twisted pseudopetiole; grain globose with thick
loose pericarp ............................................................................................................ 6. Phaenospermateae (p. 187)
7b. Leaf blades lanceolate to ovate, not pseudopetiolate or twisted; grain an ovoid to
trigonous caryopsis.
8a. Glumes persistent; lemma 3–9-veined ........................................................................ 16. Centotheceae (p. 444)
8b. Glumes deciduous; lemma 1-veined; low trailing annual ............ 25. Isachneae (182. Sphaerocaryum: p. 560)
5b. Leaf blades without cross veins, usually narrow.
9a. Inflorescence composed of one or more racemes.
10a. Spikelets in triads ........................................................................................ 15. Triticeae (100. Hordeum: p. 395)
10b. Spikelets single.
11a. Rachis fragile; glumes placed side by side ............................................ 11. Poeae (74. Parapholis: p. 315)
11b. Rachis tough; glumes opposite.
12a. Lemma 5-veined; spikelets orbicular with gibbously inflated
glumes enclosing floret .......................................................... 12. Aveneae (92. Beckmannia: p. 364)
12b. Lemma 1–3-veined; spikelets not as above ................................................ 23. Cynodonteae (p. 487)
9b. Inflorescence an open, contracted or spikelike panicle.
13a. Spikelets with 2 florets, lower floret staminate or barren, awned from
low on back, upper floret fertile ........................................................... 12. Aveneae (76. Arrhenatherum: p. 322)
13b. Spikelets with 1 to several florets (if 2 florets, lower floret fertile).
14a. Ligule a line of hairs.
15a. Lemma cleft into 7–9 awns ....................................................................... 21. Pappophoreae (p. 456)
15b. Lemma with 1 or