Key to Sporobolus

View taxon page for Sporobolus

(For a list of species in Sporobolus, use the above link.)

Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots.

1. Annual; inflorescence 1–5 cm, terminal and 

axillary 

Pertaining to or within an axil, especially a leaf axil.

at ± most stem 

nodes 

Position on a stem from which one or more structures (especially leaves, buds, branches, or flowers) arise.

; upper 

glume 

In Poaceae, each of generally two sheathing bracts that are the lowermost parts of a spikelet, subtending one or more florets.

2.5–5 mm; 

lemma 

In Poaceae, the lower, generally larger of two sheathing bracts subtending a flower, generally ensheathing the palea (in a sterile lemma, the associated flower and sometimes palea are rudimentary or absent); with the palea and flower, comprising the floret.

leathery, tip beaked ..... S. vaginiflorus

1' Perennial herb; inflorescence 8–80 cm, generally terminal, sometimes axillary at some stem nodes; upper glume 0.5–3 mm; lemma membranous, tip 

obtuse 

Having a short-tapered, blunt tip or base, the sides convex or straight and converging at more than a right angle.

to 

acute 

Having a short-tapered, sharp tip, the sides convex or straight and converging at less than a right angle.

2. Sheath collar with conspicuous hairs to 4 mm; glume back keeled, upper glume midvein ± scabrous at 20×

3. Lower 1° inflorescence branches generally < 2 cm, bearing 2° inflorescence branches and 

spikelets 

1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts.

to near base ..... S. contractus

3' Lower 1° inflorescence branches > 3 cm, bearing 2° inflorescence branches and spikelets along upper 3/4, base naked

4. 2°, 3° inflorescence branches weakly 

spreading 

Oriented more or less perpendicularly to the axis of attachment; often, more or less horizontal.

or 

appressed 

Parallel or nearly parallel to and often in contact with surface of origin; used to describe the disposition of hairs, leaves, pedicels, etc.

, ± obscure ..... S. cryptandrus

4' 2°, 3° inflorescence branches spreading, evident, entangled ..... S. flexuosus

2' Sheath collar glabrous or with sparse long hairs to 6 mm; glume back rounded, upper glume midvein ± smooth at 20×

5. Upper glume length < 0.6 × lemma, tip obtuse, minutely toothed; anthers 0.5–1.1 mm ..... S. indicus

5' Upper glume length > 0.6 × lemma, tip acute, 

entire 

Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.).

; anthers 1.1–1.8 mm

6. Stem generally 3–10 dm, to ± 3 mm thick at base; 2° inflorescence branches spreading, bearing spikelets distally, base naked, 3° inflorescence branches spreading ..... S. airoides

6' Stem generally 9–25 dm, to ± 9 mm thick at base; 2° inflorescence branches weakly spreading or appressed, bearing spikelets to near base, 3° inflorescence branches appressed ..... S. wrightii

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