Key to Eragrostis

View taxon page for Eragrostis

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

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

1. Perennial herb; 

spikelet 

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.

 axis breaking tardily above glumes and between 

florets 

In Poaceae, a single flower and its immediately subtending bracts (lemma and generally palea, the lemma subtending the palea when the latter is present); in a sterile floret, the flower and sometimes palea are rudimentary or absent.

2. Leaf 

blade 

Expanded portion of a leaf, petal, or other structure, generally flat but sometimes rolled, cylindric, wavy, or cupped.

12–50 (65) cm; spikelet 1.5–2 mm wide; 

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.

1.8–3 mm; fruit ± 1.5 mm ..... E. curvula

2' Leaf blade 2–12 cm; spikelet 0.8–1.2 mm wide; lemma 1.4–1.7 mm; fruit 0.6–0.8 mm ..... E. lehmanniana

1' Annual; spikelet axis persistent, glumes and 

lemmas 

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.

falling from axis, paleae generally persistent

3. Plants mat-forming; 

basal 

At or near the base of a plant or plant part. Especially said of leaves clustered near the ground or of a placenta confined to the base of an ovary.

portion of stem 

prostrate 

Lying flat on the ground.

, rooting at 

nodes 

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

..... E. hypnoides

3' Plants generally not mat-forming; basal portion of stem 

erect 

Upright; vertically oriented.

, not rooting at nodes

4. Fruit with 1 or both ends 

truncate 

Abruptly (not gradually) narrower or smaller at base or tip, as if cut straight across or nearly so.

; surface checkered, with an evident groove on 1 side ..... E. mexicana

5. Spikelet 

ovate 

Egg-shaped (i.e., widest below the middle) in two dimensions (i.e., in one plane), as a leaf.

to 

oblong 

Longer than wide, with nearly parallel sides; wider than linear.

, 1.5+ mm wide; inflorescence branches often with scattered glands ..... subsp. mexicana

5' Spikelet 

linear 

Elongate, with nearly parallel sides; narrower than elliptic or oblong.

to lance-linear, ± 1 mm wide; inflorescence not glandular ..... subsp. virescens

4' Fruit variously-shaped, tip rounded; surface smooth, not grooved

6. Plant without conspicuous glands or glandular areas (rarely so in Eragrostis pilosa)

7. Palea deciduous; lower 

glume 

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

< 1/2 lowest floret; lowest inflorescence branches 

whorled 

Arranged in groups of three or more at nodes or positions along an axis (e.g., three leaves per node).

..... E. pilosa var. pilosa

7' Palea persistent; lower glume > 1/2 lowest floret; inflorescence branches 

alternate 

1. Arranged singly, often spirally, along an axis - e.g., one leaf per node. 2. Occurring in different ranks, appearing to be between, not directly above or below, as 'stamens alternate petals'.

or 

opposite 

1. Arranged in pairs along an axis - e.g., two leaves per node. 2. Occurring in the same rank, directly above or below, as 'stamens opposite petals'. 3. Located directly across from.

..... E. pectinacea

8. Spikelet stalks 

spreading 

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

..... var. miserrima

8' Spikelet stalks 

appressed 

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

to branches, diverging < 20° ..... var. pectinacea

6' Plant with conspicuous glands or glandular areas on 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

 

sheath 

A surrounding or partially surrounding, often tubular structure or part of a structure, such as a leaf base in Apiaceae or Poaceae.

, blade margin, inflorescence axis and branches, spikelet stalk, or lemma keel

9. Inflorescence contracted, 0.5–2 cm wide, 1° branches generally 

ascending 

Curving or angling upward from base, or about 30-60 degrees less than vertical or away from axis of attachment.

to appressed; 

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.

light yellow ..... E. lutescens

9' Inflorescence open to contracted, 2–18 cm wide, 1° branches diverging; spikelets ± green, red-purple, or lead-colored

10. Spikelets 2–4 mm wide; glume and lemma keels glandular; anthers yellow ..... E. cilianensis

10' Spikelets 1.1–2.2 mm wide; glume and lemma keels not glandular; anthers red-brown

11. Anthers 2; spikelet stalks generally with a distal ring of cup-shaped glands; lemma keels sometimes glandular ..... E. minor

11' Anthers 3; spikelet stalks without a distal ring of cup-shaped glands; lemma keels not glandular ..... E. barrelieri

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