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Mexican panicgrass, roughstalk witchgrass, roughstalk wltchgrass, woodland panic

prairie panicgrass

Habit Plants annual; glabrous or hispid, hairs papillose-based. Plants annual; weak, ascending or spreading.
Culms

11-110 cm, erect to decumbent;

nodes shortly hirsute or glabrous.

slender, wiry, glabrous, often with minute purple streaks and dots, ascending from a decumbent base, often branching extensively at the base and rooting at the lower nodes.

Sheaths

shorter than the internodes, greenish to purplish, glabrous or with papillose-based hairs, ciliate on 1 margin, glabrous on the other;

collars hirsute;

ligules 1.5-3.5 mm, of hairs;

blades 3-30 cm long, 3-30 mm wide, flat, usually hirsute or sparsely pubescent, hairs papillose-based, sometimes glabrous, bases rounded to cordate-clasping, margins ciliate, cilia papillose-based, apices acute.

usually shorter than the internodes, glabrous, margins short-ciliate;

ligules usually less than 0.3 mm, membranous, erose, ciliate;

blades 4-15 cm long (rarely longer), 2-3 mm wide, flat or slightly involute, glabrous on both surfaces, margins scabridulous, especially towards the apices, bases narrowed.

Panicles

9-30 cm long, 5-8 cm wide, erect or nodding, partially included to well-exserted, rachises glabrous or sparsely hispid basally;

primary branches usually alternate to opposite, divergent, secondary branches and pedicels confined to the distal 2/3;

pulvini inconspicuous;

secondary branches appressed;

pedicels 9-27 mm, appressed.

4-17 cm, 1/2 to nearly as wide as long;

branches few, capillary, ascending or spreading, scabridulous, with a few spikelets distally;

pedicels 0.5-10 mm.

Spikelets

1.9-4 mm long, 0.8-1 mm wide, ovoid to almost spherical, often reddish-brown, glabrous, veins prominent, scabridulous, apices abruptly acuminate.

3.2-4 mm long, about 1.5 mm wide, broadly ellipsoid or obovoid, tuberculate, hispid, faintly veined, acute or acuminate at the apices.

Lower glumes

1.3-2.4 mm, 1/2 - 3/4 as long as the spikelets, 3-5-veined;

upper glumes 1.8-3.3 mm, 7-11-veined;

lower florets sterile;

lower lemmas similar to the upper glumes, 9-veined;

lower paleas 0.4-0.9 mm;

upper florets 1.5-2.4 mm long, 0.4-0.8 mm wide, ellipsoid, smooth or conspicuously papillate, shiny, stramineous, often with a lunate scar at the base.

usually less than 1 mm, obtuse or acute;

upper glumes and lower lemmas subequal, distinctly tuberculate, hispid, with stiff hairs arising from wartlike bases;

upper florets 2.7-3.2 mm long, 1.3-1.6 mm wide, obovoid or ellipsoid, nearly smooth, minutely papillose, or cross-rugulose, subacute to acute.

2n

= unknown.

Panicum hirticaule

Panicum brachyanthum

Distribution
from FNA
AZ; CA; NM; NV; OK; TX; WA
[WildflowerSearch map]
[BONAP county map]
from FNA
AR; LA; MS; OK; TX
[WildflowerSearch map]
[BONAP county map]
Discussion

Panicum hirticaule grows in rocky or sandy soils in waste places, roadsides, ravines, and wet meadows along streams. Its range extends from southeastern California and southwestern Texas southward through Mexico, Central America, Cuba, and Hispaniola to western South America and Argentina.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Panicum brachyanthum grows in dry, sandy or clayey soils of open areas, remnant prairies, woodland borders, and roadsides and, less commonly, along the margins of bogs and on grassy shores in the western portion of the gulf coast plain. It is restricted to the southern United States. It resembles P. verrucosum in its growth habit, but is more restricted in its distribution.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Blades rounded at the base, 3-16 mm wide; lower paleas less than 1/2 as long as the upper florets; panicles erect
subsp. hirticaule
1. Blades cordate, clasping at the base, 4-30 mm wide; lower paleas more than 1/2 as long as the upper florets; panicles often nodding.
→ 2
2. Nodes, sheaths, and blades glabrous or sparsely pilose, hairs papillose-based; culms usually less than 70 cm tall; spikelets 3.2-4 mm long
subsp. stramineum
2. Nodes, sheaths, and blades hirsute, hairs papillose-based; culms robust, usually more than 70 cm tall; spikelets 3-3.3 mm long
subsp. sonorum
Source FNA vol. 25, p. 460. FNA vol. 25, p. 487.
Parent taxa Poaceae > subfam. Panicoideae > tribe Paniceae > Panicum > subg. Panicum > sect. Panicum Poaceae > subfam. Panicoideae > tribe Paniceae > Panicum > subg. Phanopyrum > sect. Verrucosa
Sibling taxa
P. amarum, P. anceps, P. antidotale, P. bergii, P. bisulcatum, P. brachyanthum, P. bulbosum, P. capillare, P. capillarioides, P. coloratum, P. dichotomiflorum, P. diffusum, P. flexile, P. ghiesbreghtii, P. gymnocarpon, P. hallii, P. hemitomon, P. hirsutum, P. lacustre, P. miliaceum, P. mohavense, P. obtusum, P. paludosum, P. philadelphicum, P. plenum, P. psilopodium, P. repens, P. rigidulum, P. tenerum, P. trichoides, P. urvilleanum, P. verrucosum, P. virgatum
P. amarum, P. anceps, P. antidotale, P. bergii, P. bisulcatum, P. bulbosum, P. capillare, P. capillarioides, P. coloratum, P. dichotomiflorum, P. diffusum, P. flexile, P. ghiesbreghtii, P. gymnocarpon, P. hallii, P. hemitomon, P. hirsutum, P. hirticaule, P. lacustre, P. miliaceum, P. mohavense, P. obtusum, P. paludosum, P. philadelphicum, P. plenum, P. psilopodium, P. repens, P. rigidulum, P. tenerum, P. trichoides, P. urvilleanum, P. verrucosum, P. virgatum
Subordinate taxa
P. hirticaule subsp. hirticaule, P. hirticaule subsp. sonorum, P. hirticaule subsp. stramineum
Synonyms P. pampinosum
Name authority J. Presl Steud.
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