keys to the vascular plants of east texas - Botanical Research ...

996 POACEAE/PANICUM
Panicum antidotale Retz., (acting as or of the nature of an antidote), BLUE PANIC, BLUE PANIC
GRASS. Rhizomatous perennial 0.5–2(–3) m tall; ligule 1.5 mm or less long; rhizomes ca. 1 cm
thick; culms becoming almost woody (bamboo-like), much-branched, knobby, the swollen
nodes conspicuously thicker than the internodes; spikelets 2.4–3.4 mm long; lower glume 1/2
as long as spikelet or less, rounded to obtuse apically. Recommended by some for planting as a
forage grass and used in range reseeding (Gould 1975b); Bexar, Brazos, McLennan, and Travis
(Turner et al. 2003) cos.; widely scattered in TX, but primarily s 1/2; sporadically across the s 1/
3 of the U.S. from NC s to FL w to CA. Spring–fall. Native of India. This species is considered a
noxious weed in CA (Kartesz 1999). � I
Panicum bergii Arechav., (for F.G.C. Berg, former director of the Museo Nacional de Buenos Aires,
Argentina), BERG’S WITCHGRASS. Tufted perennial 50–100(–140) cm tall; lower nodes with a collar
of hairs; leaves with sheaths glabrous or often sparsely to densely pilose, the blades densely
so at base; ligule a short membranous base ca. 0.5 mm long with fringe of hairs to 3 mm long;
panicles ca. 1/3–1/2 the height of the entire plant, open, the whole inflorescence detaching as a
tumbleweed at maturity, the lower panicle branches in verticils of 3–7, stiffly spreading, the
secondary branches usually from distal 1/3 of primary branches; spikelets glabrous, 2–3 mm
long. Low areas, ditches; Austin, Brazos, Navarro (BRIT), Colorado, Harris, and Waller (Turner et
al. 2003) cos.; also Gulf Prairies and Marshes and McMullen Co. (Turner et al. 2003) in the South
TX Plains; AL and TX. Late Apr–May. Native of e South America. [P. pilcomayense Hack.] While
this species was long treated as P. pilcomayense, P. bergii is an older name and thus has nomenclatural
priority. I
Panicum brachyanthum Steud., (short-flowered), PIMPLE PANICUM, PRAIRIE PANIC GRASS. Largely
glabrous annual with erect to decumbent culms to ca. 100 cm long; ligule usually 0.3 mm or
less long; leaf blades 1–3 mm wide; panicles few-flowered; spikelets 3–3.6(–4) mm long, conspicuously
warty, covered with short stiff hairs. Open, often sandy woods, fencerows, along
highways, relatively dry habitats; Pineywoods and Post Oak Savannah; also Gulf Prairies and
Marshes; AR, GA, LA, MS, OK, and TX. Aug–Nov. This species resembles P. verrucosum, also
with warty spikelets—however, that species has glabrous, much smaller spikelets only 1.7–2.5
mm long, broader leaf blades, and a preference for wetter habitats.
Panicum bulbosum Kunth, (bulbose), BULB PANIC GRASS. Rhizomatous perennial; culms 1.4(–2)
m or less tall, usually with swollen, corm-like bases; spikelets usually 2.8–4.2(–5.4) mm long;
fertile floret finely transversely rugose. Gravelly river banks; Bexar and Bell (Turner et al. 2003)
cos.; mainly w 1/3 of TX; AZ, NM, NV, and TX. (Jul–)Aug–mid-Oct. This species is used in parts
of its range as a forage grass and for hay (Freckmann & Lelong 2003b). The county distribution
map includes plants sometimes treated as P. plenum Hitchc. & Chase. Freckmann and Lelong
(2003b) recognized these plants as a distinct species, based on smaller spikelets (2.5–3.4 mm
long), longer rhizomes, and culm bases not swollen. Hatch (2002) did not mention P. plenum,
and Turner et al. (2003) included it in P. bulbosum. Additional work needs to be done to determine
the appropriate disposition of these taxa.
Panicum capillare L., (hair-like), WITCH GRASS. Annual with erect to partly decumbent culms
usually (8–)20–100 cm long; leaf blades usually hirsute or pilose on both surfaces or glabrous
on the upper surface (occasionally merely ciliate marginally below); leaf sheaths with papillabased
hairs; ligule of hairs, 2 mm or less long; inflorescence very open (the branches widely
spreading to spreading-ascending), large for size of plant (often � 1/2 height of plant), often
with reddish or purplish coloration; peduncle often detaching at maturity and the inflorescence
acting as a tumbleweed (Crins 1991; Freckmann & Lelong 2003b); spikelets 1.4–3.5(–4)
mm long; palea of lower floret usually absent (do not be confused by lodicules); lemma of fertile
floret without a crescent-shaped marking at base. Open areas, disturbed sites, and banks of
ponds and streams; widespread in TX; s Canada and nearly throughout the U.S. May–Nov. This