keys to the vascular plants of east texas - Botanical Research ...

POACEAE
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6. Lemmas awned, the twisted and geniculate awns usually (3–)5–12(–17) mm long; spikelets
7–18(–20) mm long; inflorescences 12 cm or less long _________________________ Danthonia
4. Glumes not conspicuously longer than individual lemmas.
7. Lemmas with 11–15 awns __________________________________________________ Pappophorum
7. Lemmas awnless or with a single awn.
8. Spikelets in several very dense, � 1-sided clusters at the ends of branches, the branches
bare of spikelets in their lower portions; rare introduced species _______________________ Dactylis
8. Spikelets not borne as above; including common native and introduced species.
9. Lemmas 3-veined, the veins often prominent.
10. Veins of lemmas pubescent or puberulent OR base of lemmas with long hairs;
lemmas with midvein usually exserted as a short awn or mucro.
11. Plants annual; spikelets usually with (2–)3–4 florets; inflorescence a panicle
3–11 cm long with a few rebranched primary branches, the lower branches
bare of spikelets on the lower 1/3–1/2; nerves of paleas with long hairs on
upper half _________________________________________________________ Triplasis
11. Plants perennial; spikelets with 3–12 florets; inflorescences various, but often
quite different from above; nerves of paleas without long hairs on upper half.
12. Inflorescences 5–40 cm long; culms with several nodes above base; leaf
margins green, not thickened _______________________________________ Tridens
12. Inflorescences 2–4(–6) cm long; culms with one node above base; leaf
margins white, thickened (visible with a hand lens) ___________________ Erioneuron
10. Veins of lemmas not hairy; base of lemmas without long hairs; lemmas awnless.
13. Lower 1(–2) floret(s) sterile; stamen 1 per floret; spikelets flat, 4–9 mm long, (2–)
3–5(–6) mm wide _____________________________________ Chasmanthium (C. laxum)
13. Lower florets fertile; stamens 2–3 per floret; spikelets variously shaped and
sized.
14. Lemmas 4.6–10.8 mm long; upper glume with 3–5 veins; caryopsis (= fruit)
beaked, conspicuously exserted from the lemma and palea at maturity;
species rare in East TX, documented only from Dallas Co. ________________ Diarrhena
14. Lemmas 0.7–5 mm long; upper glume with 1 vein; caryopsis neither
beaked nor conspicuously exserted; including species widespread and
abundant in East TX.
15. Lemmas white, often purplish distally, the spikelets thus often appearing
banded; inflorescence contracted, 1.5 cm or less wide,
densely-flowered, the branches usually with spikelets nearly to base
or apparently so (branches usually tightly appressed at base); spikelets
4–10 mm long __________________________________ Tridens (T. albescens)
15. Lemmas variously colored; inflorescences variously shaped; spikelets
of various sizes ______________________________________________ Eragrostis
9. Lemmas 5–many-veined, the veins prominent or sometimes so obscure as to be almost
unnoticeable.
16. Lemmas awned.
17. Spikelets usually (10–)15–50 mm long, if spikelets at the lower end of this
size range, then lemmas 2-toothed or minutely notched at apex _______________ Bromus
17. Spikelets 15.5(–18) mm or less long (often much less), if spikelets at the upper
end of this size range, then lemmas neither 2-toothed nor notched at apex.
18. Lemmas awned from (or just below) a conspicuously 2-toothed apex,
the awn geniculate _______________________________________________ Trisetum
18. Lemmas awned from an entire or minutely and indistinctly notched apex,
the awn straight.
19. Inflorescences dense, spike-like, uninterrupted panicles; lemmas
keeled on back; awns 1–3 mm long ______________________________ Rostraria