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Hall panicum, Hall's panic, Hall's panicgrass, Hall's panicum, Hall's witchgrass

spreading witchgrass, West Indian panicgrass

Habit Plants perennial; cespitose. Plants perennial; cespitose and shortly rhizomatous.
Culms

10-100 cm, 2-10 mm thick, erect, simple or sparingly branched basally;

nodes sericeous, pilose or glabrous;

internodes usually glaucous.

(6)25-100 cm, 0.5-3.5 mm thick, spreading to weakly ascending, usually freely branching;

nodes pilose, hairs spreading to ascending;

internodes pilose, with papillose-based hairs, or sparsely hispid.

Sheaths

rounded, glabrous, margins shortly ciliate distally;

ligules 0.6-4 mm, of hairs;

blades (3)6-15 cm long, 1-5 mm wide, spreading, abaxial surfaces sparsely hirsute, adaxial surfaces more densely so, hairs papillose-based, midribs prominent and not white, margins involute, bases cuneate, apices subulate.

Leaves

often crowded basally;

sheaths rounded, glabrous or hirsute, hairs fragile, papillose-based, margins sometimes ciliate distally;

ligules 0.6-2 mm;

blades 4-23 cm long, 1-10 mm wide, erect to spreading, flat or sometimes involute (on sterile branches), often curling at maturity, glaucous, abaxial surfaces sometimes with prominent papillae along the midribs, bases rounded or narrowing to the sheaths, margins cartilaginous, ciliate basally, scabridulous elsewhere, apices acute.

Spikelets

2.1-4.2 mm long, 0.8-1 mm wide, usually ovoid, glabrous.

2.1-2.9 mm long, 0.8-1 mm wide, glabrous.

Lower glumes

1.2-2.4 mm, 1/2 - 3/4 as long as the spikelets, attenuate;

upper glumes and lower lemmas similar, 7-11-veined, acuminate, extending 0.3-1.2 mm beyond the upper florets;

lower florets sterile;

lower paleas 0.8-2 mm;

upper florets 1.5-2.4 mm long, 0.7-1.2 mm wide, ovoid to ellipsoid, smooth, nigrescent.

1-1.2 mm, to 1/2 as long as the spikelets, attenuate, 5-9-veined, veins anastomosing apically;

upper glumes and lower lemmas similar, extending about 0.5 mm beyond the upper florets, 11-13-veined;

lower florets sterile;

lower paleas 1-1.3 mm;

upper florets 1.5-1.8 mm long, 0.6-0.8 mm wide, smooth.

Terminal

panicles 7-31 cm long, 3-15 cm wide;

rachises glabrous, tending to break at maturity;

branches usually alternate, slender, stiff, ascending to divergent;

pedicels 1-15 mm, appressed.

panicles 3-35 cm long, about 1/2 as wide, shortly exserted;

axillary panicles smaller, not fully exserted;

rachises scabridulous;

primary branches usually solitary, sometimes paired, divergent and widely spaced, secondary branching mostly on the distal 1/3 of the primary branches;

pedicels 1-4 mm, spreading to appressed, confined to the distal portions of the secondary branches.

2n

= 18.

= 36.

Panicum hallii

Panicum diffusum

Distribution
from FNA
AZ; CO; LA; NM; OK; TX; UT
[WildflowerSearch map]
[BONAP county map]
from FNA
LA; TX; PR; Virgin Islands
[BONAP county map]
Discussion

Panicum hallii grows on sandy, gravelly, or rocky land, including roadsides, pastures, rangeland, oak and pine savannahs, chaparral, and moist areas in deserts and on mesas. Its range extends from the southwestern United States to southern Mexico.

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

Panicum diffusum grows along river banks, ditches, and disturbed areas in wet, loamy or clayey soils. Its range extends from Texas to the Caribbean and northern South America.

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

Key
1. Spikelets 3-4.2 mm long; panicles usually greatly exceeding the blades, with a few spikelets; blades clustered near the base of the plants, ascending, often curling at maturity
subsp. hallii
1. Spikelets 2.1-3 mm long; panicles scarcely exceeding the blades, with relatively crowded spikelets; blades not clustered near the base of the plants, lax, spreading, not curled
subsp. filipes
Source FNA vol. 25, p. 466. FNA vol. 25, p. 466.
Parent taxa Poaceae > subfam. Panicoideae > tribe Paniceae > Panicum > subg. Panicum > sect. Panicum Poaceae > subfam. Panicoideae > tribe Paniceae > Panicum > subg. Panicum > sect. Panicum
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. 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
P. amarum, P. anceps, P. antidotale, P. bergii, P. bisulcatum, P. brachyanthum, P. bulbosum, P. capillare, P. capillarioides, P. coloratum, P. dichotomiflorum, 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. hallii subsp. filipes, P. hallii subsp. hallii
Synonyms P. lepidulum
Name authority Vasey Sw.
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