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Spikelets

As noted under Synflorescence characters, we interpret the spikelet (or spikelet proper of a pseudospikelet) as a bracteate spike, which thus represents the true inflorescence in grasses (Stapleton 1997 and others). Based on this interpretation, the main axis (rachilla) of the spikelet becomes a rachis and the pedicel becomes a peduncle, so we use this terminology here.

SP-1. Compression of florets: 0 = terete; 1 = lateral; 2 = dorsal.

SP-2. Number of glumes (in female-fertile spikelets or spikelets proper): 0 = absent; 1 = one; 2 = two; 3 = three; 4 = four; 5 = five or six.

SP-3. Lowermost glume (glume I) development: 0 = well developed; 1 = strongly reduced, scalelike.

SP-4. Apex of lowermost glume: 0 = obtuse/truncate; 1 = acute; 2 = mucronate; 3 = awned.

SP-5. Next higher glume (glume II) development: 0 = well developed; 1 = strongly reduced, scalelike.

SP-6. Apex of next higher glume: 0 = obtuse/truncate; 1 = acute; 2 = mucronate; 3 = awned.

SP-7. Number of female-fertile florets per spikelet or spikelet proper: 0 = one; 1 = two; 2 = three or more.

SP-8. Floret sexuality: 0 = bisexual; 1 = unisexual.

SP-9. Rachis extension (internode only, with or without rudimentary floret): 0 = absent; 1 = present.

SP-10. Relative length of the rachis extension (internode only, with or without rudimentary floret) when present: 0 = short (shorter than or equal to about half the length of the floret); 1 = long (approximately equal to or longer than the floret).

SP-11. Rachis extension (internode only): 0 = glabrous; 1 = hairy.

SP-12. Rudimentary floret on the rachis extension: 0 = absent; 1 = present.

SP-13. Female-fertile lemma nerve number: 0 = 1; 1 = 3; 2 = 5 or more.

SP-14. Female-fertile lemma shape: 0 = navicular; 1 = spindle-shaped; 2 = ellipsoid; 3 = helmet-shaped.

SP-15. Female-fertile lemma apex shape: 0 = obtuse; 1 = acute; 2 = mucronate; 3 = awned.

SP-16. Female-fertile lemma apex fusion (exclusive of the awn or mucro if present): 0 = margins free; 1 = margins fused (connate).

SP-17. Female-fertile lemma texture: 0 = chartaceous (membrano-chartaceous); 1 = rigid, hardened.

SP-18. Palea keels: 0 = bicarinate (2-keeled); 1 = 1-keeled; 2 = rounded (keels not evident).

SP-19. Palea keel wings: 0 = absent; 1 = present.

SP-20. Palea apex: 0 = biapiculate (sinus shallow); 1 = tips long-divided (sinus deep); 2 = acute, not divided.

SP-21. Palea sulcus: 0 = well developed for full length of palea; 1 = well developed only toward the apex; 2 = absent.

Life Span and Rhizomes
Culms
Buds and Branching
Culm Leaves
Foliage Leaves
Synflorescences
Spikelets
Flowers and Fruits
Leaf Anatomy
Leaf Micromorphology

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