What’s a dichotomous key?
Help
Glyceria
See list of 11 species in this genusThe genera Glyceria, Puccinellia, and Torreyochloa are often confused because of superficial similarities in morphology and occurrence in hydric habitats. Among these three genera, only Glyceria has closed leaf sheaths and 1-veined upper glumes (the other two genera have open leaf sheaths and 3-veined upper glumes). Only Puccinellia is tolerant of saline conditions and has inconspicuous veins on the lemmas (the other two genera are restricted to freshwater habitats and generally have conspicuous veins on the lemmas). Reference: Barkworth and Anderton (2007).
-
1a. Spikelets 10–40 mm long, with 7–16 florets [Fig. 231]; internodes of the rachilla 1–4 mm long; stamens 3 per floret; sheaths conspicuously compressed
-
2a. Spikelets 20–40 mm long; lemmas 7–8.5 mm long, acute at the apex [Fig. 231]; paleas exceeding lemmas by 1.5–3 mm
-
2b. Spikelets 10–20 mm long; lemmas 3.1–7 mm long, truncate to obtuse at the apex; paleas equaling or exceeding lemmas by no more than 1 mm
-
3a. Lemmas glabrous between the veins (infrequently minutely scabrous), 3.1–3.9 mm long, the veins terminating ca. 0.2 mm from the lemma apex; anthers 0.6–1 mm long; internodes of rachilla 1–1.3 mm long; mid-stem leaf blades minutely, but densely, papillose on the adaxial surface
-
3b. Lemmas scabrous between the veins, 3.7–7 mm long, the veins extending to within 0.1 mm of lemma apex; anthers 1–3 mm long; internodes of rachilla 1.1–2.5 mm long; mid-stem leaf blades smooth or scabridulous (sometimes minutely papillose in G. septentrionalis)
-
4a. Lemmas 3.7–5.3 mm long; internodes of rachilla 1.1–1.8 mm long; anthers 1–1.7 mm long; adaxial surface of the mid-stem leaf blades sometimes minutely papillose
-
4b. Lemmas 5.4–7 mm long; internodes of rachilla 1.9–2.5 mm long; anthers 2–3 mm long; adaxial surface of the mid-stem leaf blades smooth
-
-
-
-
1b. Spikelets 2–8 mm long, with 3–10 florets [Fig. 232]; internodes of the rachilla shorter than 1 mm; stamens 2 or 3 per floret; sheaths not conspicuously compressed
-
5a. Panicle dense, with strictly ascending to erect branches; ligules 0.5–0.9 mm long
-
6a. Inflorescence arching to nodding, narrow-cylindric, with 1–3 branches at each node, mostly 15–25 cm long; internodes of the inflorescence 2–7 cm long; spikelets 3.5–5 mm long; new stem leaves numbering 3–6 per stem
-
6b. Inflorescence erect, ovoid to obloid [Fig. 233], with 3–8 branches at each node, mostly 5–15 cm long; internodes of the inflorescence up to 2.5 cm long, commonly less than 2 cm; spikelets 4–7 mm long; new stem leaves numbering 7–9 per stem
-
-
5b. Panicle open, the branches ascending to drooping; ligules 1–6 mm long
-
7a. Spikelets (2.5–) 3–5 mm wide; veins of the lemma visible but not raised; palea less than 2 times as long as wide
-
8a. Lemmas (2.4–) 2.9–4 mm long, acute at the apex, projecting beyond the paleas at least 0.5 mm; spikelets 5–8 mm long, with 4–10 florets; upper glume acute at the apex [Fig. 232]
-
8b. Lemmas 1.8–2.5 (–2.9) mm long, obtuse at the apex, not, or scarcely, exceeding the associated paleas; spikelets 4–5 mm long, with 2–5 florets; upper glumes rounded at the apex (rarely varying to acute)
-
-
7b. Spikelets 1.5–2.5 mm wide; veins of the lemma conspicuous and raised; palea 3–5 times as long as wide
-
9a. Spikelets 2–4.5 mm long; glumes obtuse, the first and second 0.5–1 mm and 0.8–1.3 mm long, respectively; lemmas firm, caducous; stamens 2 per floret; new cauline leaves 5–10 per stem
-
9b. Spikelets 4–6.5 mm long; glumes acute, the first and second 1.2–1.9 mm and 1.5–2.4 mm long, respectively; lemmas membranaceous, deciduous; stamens mostly 3 per floret; new cauline leaves 3–6 per stem
-
10a. Leaves with blades 4.5–12 (–15) mm wide and usually smooth sheaths; second glume 1.5–2.7 mm long; apex of lemma ± flat; anthers 0.5–1.2 mm long
-
10b. Leaves with blades (6–) 8–18 (–20) mm wide and minutely scabrous sheaths; second glume (2.5–) 3–4 mm long; apex of lemma cucullate; anthers (1–) 1.2–2 mm long
-
-
-
-
Show photos of:
Each photo represents one species in this genus.