Key to Panicum

View taxon page for Panicum

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

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

1. Leaves in 2 forms, 

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.

< and generally wider than cauline, 

rosette 

A radiating cluster of leaves generally at or near ground level.

well developed, generally persistent; main 

panicle 

1. In flowering plants excluding Asteraceae, Cyperaceae, Poaceae, and some other groups, a branched inflorescence in which the basal or lateral flowers (or some of them) open before the terminal or central flowers on any axis. 2. In Asteraceae, Cyperaceae, Poaceae, and some other groups, a panicle-like inflorescence is one in which at least some of the inflorescence units (e.g., heads in Asteraceae; spikelets in Cyperaceae and Poaceae), instead of individual flowers, are attached (stalked or unstalked) to branches and not directly to the main axis of the inflorescence and in which floral development may or may not proceed as in 1.

branches 

forked 

Pertaining to a hair or other structure that branches into two parts.

at base (subg. Dichanthelium)

2. Spikelet 2.7–3.5 mm, 2–2.4 mm wide; upper 

glume 

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

9-veined with a prominent orange spot at base, lower glume 

acuminate 

Having a long-tapered, sharp tip, the sides concave.

; 

ligule 

1. In Asteraceae, the 5-lobed, strap- or fan-shaped outer portion of the corolla of a ligulate flower. 2. In most Poaceae and some other grass-like plants, an appendage at the adaxial junction of leaf sheath and blade, generally membranous, sometimes formed of hairs. 3. In Isoetes and, more obscurely, in Selaginella, a membrane that wholly or partially covers a sporangium.

 hairs 1–1.5 mm ..... P. oligosanthes var. scribnerianum

2' Spikelet 1–2 mm, ± < 1 mm wide; upper glume 7-veined, lacking orange spot at base, lower glume 

acute 

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

; ligule of hairs 2–4 mm ..... P. acuminatum

3. Stem, lower 

sheath 

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

generally glabrous ..... var. lindheimeri

3' Stem, sheath soft-hairy

4. Leaf 

blade 

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

 

puberulent 

Minutely hairy.

abaxially; inflorescence generally long-exserted ..... var. fasciculatum

4' Leaf blade soft-hairy abaxially; inflorescence generally scarcely 

exserted 

Protruding out of surrounding structure(s) (e.g., stamens exserted from corolla).

..... var. thermale

1' Leaves gradually reduced upward, basal rosette not well developed; main panicle branches 

simple 

Composed of a single part; undivided; unbranched.

at base (subg. Panicum)

5. Sheath compressed-keeled, blade folded at base; ligule ragged ..... P. rigidulum subsp. rigidulum

5' Sheath not compressed-keeled, blade flat or rolled under; ligule 

ciliate 

Having generally straight, conspicuous hairs along margins or edges.

6. Perennial herb, generally with rhizomes or stolons; lower floret staminate

7. Stem hard, almost woody; upper 

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.

with flat margin ..... P. antidotale

7' Stem not especially hard; upper lemma margin inrolled ..... P. urvilleanum

6' Annual; lower floret sterile

8. Stem, leaves ± glabrous; lower glume ± 

truncate 

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

, < 1/3 

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.

length ..... P. dichotomiflorum subsp. dichotomiflorum

8' Stem, leaves hairy; lower glume acute, > 1/3 spikelet length

9. Spikelet > 4 mm; panicle dense, 

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.

in overlapping clusters ..... P. miliaceum subsp. miliaceum

9' Spikelet < 4 mm; panicle open, most spikelets well separated

10. Lower 

palea 

1. In Asteraceae, a scale-like bract that subtends an individual flower on the receptacle (equal to 'chaff scale' in TJM), absent in some genera, restricted to a ring separating ray and disk flowers in most tarweed species. 2. In Poaceae, the distal, generally smaller of two sheathing bracts subtending a flower, generally two-veined and -keeled and ensheathed by the lemma; with the lemma and flower, comprising the floret.

0; base of upper floret without paired crescent-shaped 

scars 

Mark left by the natural separation of two structures, as a leaf scar on a stem.

..... P. capillare

10' Lower palea present; base of upper floret generally with paired crescent-shaped scars

11. Spikelet axis not elongated between glumes and 

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.

; lower glume 1–1.5 mm, < 1/2 spikelet length; stalks generally 

spreading 

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

, generally > 2 mm ..... P. hillmanii

11' Spikelet axis ± elongated between glumes and florets, visible; lower glume 1.5–2.5 mm, > 1/2 spikelet length; stalks generally 

appressed 

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

, generally < 2 mm ..... P. hirticaule subsp. hirticaule

Please use this Google Form for Contact/Feedback

Citation for the whole project: Jepson Flora Project (eds.) . Jepson eFlora, https://ucjeps.berkeley.edu/eflora/ [accessed on ]

Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on .

We encourage links to these pages, but the content may not be downloaded for reposting, repackaging, redistributing, or sale in any form, without written permission from The Jepson Herbarium.