Panicum flexile
Panicum rigidulum
panic flexible, wiry panic grass, wiry witch grass
redtop panic grass, redtop panicum, smooth witchgrass
10-75 cm, about 1 mm thick, simple or with erect basal branches;
nodes densely pilose, hairs ascending;
internodes glabrous or shortly pubescent distally.
35-150 cm, stout, compressed.
longer than the internodes, green to purplish, hispid, margins sparsely ciliate;
ligules 0.5-1.5 mm;
blades 3-32 cm long, 1-7 mm wide, ascending to erect, linear, narrowing basally, flat or the margins involute, surfaces sparsely hirsute or pilose (rarely glabrous), hairs near the base papillose-based, margins prominent, apices acute.
more or less strongly compressed or keeled, sides usually glabrous or sparsely pubescent distally;
ligules 0.3-3 mm, membranous, erose or ciliate, cilia often themselves fimbriate;
blades 8-50 cm long, 2-12 mm wide, flat or folded, both surfaces usually glabrous or scabridulous, or the adaxial surfaces sparsely pilose basally.
5-45 cm long, 1-6 cm wide, at least 1/2 as long as the plants and 3 times longer than wide, open;
rachises glabrous;
primary branches usually alternate or subopposite, ascending to slightly divergent, secondary branches and pedicels attached to the distal 2/3;
secondary branches diverging;
pedicels 0.5-17 mm, ascending to appressed.
terminal and axillary, 9-40 cm, 1/3 – 3/4 as wide as long, usually dense; ultimate branchlets usually appressed, 1-sided, scabridulous;
pedicels 0.5-1.5 mm, usually appressed, sometimes with 1-several slender hairs at the apices.
2.5 - 3.7 mm long, 0.6-1.1 mm wide, narrowly ovoid, glabrous, acute;
lower glumes 0.8-1.3 mm, 1/3 – 1/2 as long as the spikelets, acuminate;
upper glumes 2.3-3.3 mm, 7-9-veined, exceeding the upper florets by about 0.6 mm;
lower florets sterile;
lower lemmas 2.2-2.7 mm, exceeding the upper florets by about 0.6 mm, 7- or 9-veined, apices scabridulous, pointed;
lower paleas absent;
upper florets 1.6-1.7 mm long, about 0.6 mm wide, usually smooth, usually pale, sometimes becoming dark at maturity.
usually 1.6-3.8 mm, usually subsessile, lanceolate, green, purple-tinged, or purple, glabrous.
2/5 – 3/4 as long as the spikelets, 3-veined, midveins keeled;
upper glumes and lower lemmas subequal or the glumes slightly longer, often spreading slightly apart at the apices, midveins keeled, usually scabridulous apically;
lower florets sterile;
lower paleas to 2/3 as long as the lower lemmas;
upper florets 1.4-2 mm long, 0.6-0.8 mm wide, 2/5 – 3/4 as long as the spikelets, occasionally stipitate, lustrous, with a tuft of minute, thickish hairs at the apices;
upper lemmas thick, stiff, clasping the upper paleas throughout their length.
= 18.
=18.
Panicum flexile
Panicum rigidulum
Panicum flexile grows in fens and other calcareous wetlands, in dry, calcareous or mafic rock barrens, and in open woodlands, especially on limestone derived soils. It is restricted to the Flora region.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Panicum rigidulum grows in swamps, wet woodlands, flood-plain forests, wet pine savannahs, marshy shores of rivers, ponds, and lakes, drainage ditches, and other similar wet to moist places; it is rarely found in dry sites. Its range extends from southern Canada to Mexico, Guatemala, and the Antilles.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Sheaths truncate or broadly auriculate; blade bases much narrower than the subtending sheaths | subsp. abscissum |
1. Sheaths not truncate or broadly auriculate; blade bases about as wide as the subtending sheaths. | → 2 |
2. Blades usually 5-12 mm wide, flat, mostly glabrous or scabridulous; ligules membranous, 0.3-1 mm long. | → 3 |
3. Spikelets 1.6-2.5 mm long, usually over 0.6 mm wide, green or purplish-tinged | subsp. rigidulum |
3. Spikelets 2.4-3 mm long, usually less than 0.6 mm wide, conspicuouly stipitate, usually purple | subsp. elongatum |
2. Blades usually 2-7 mm wide, often folded or involute, usually pilose adaxially, at least near the base; ligules membranous, the cilia usually fimbriate, 0.5-3 mm long. | → 4 |
4. Spikelets 2-2.7 mm long, green or purplish-stained, often obliquely set on the pedicels | subsp. pubescens |
4. Spikelets 2.6-3.8 mm long, usually purple, slender, erect on the pedicels | subsp. combsii |
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