Desert Panicgrass

Panicum urvilleanum Kunth, Rev. Gram. 403. 1831
Panicum megastachyum J. Presl, in Presl, Rel. Haenk. 1: 305. 1830. Not P. megastachyum Nees, 1826.
Panicum Preslei Kunth, Enum. 1: 121. 1833.
Panicum Urvilleanum longiglume Scribn. Bull. U. S. Dep. Agr. Agrost. 17: ed. 2. 49. 1901.
Plants robust, erect from a creeping rootstock, 0.5-1 meter high; culms solitary or few in a tuft, simple or branching at the base only, the nodes densely bearded, rarely visible; leafsheaths overlapping, loose, densely, retrorsely, harshly villous; ligule densely ciliate, about 2 mm. long; blades 30-60 cm. long, 4^7 mm. wide, tapering from a flat base to a long involutesetaceous point, retrorsely strigose to nearly glabrous on both surfaces; panicles short-exserted, equaled or exceeded by the upper blades, 25-30 cm. long, about half as wide, rather manyflowered, the glabrous to pilose, slender, flexuous branches ascending, producing spikeletbearing branchlets along the upper half to two thirds of their length; spikelets short-pediceled, 6-7 mm. long, about 2 mm. wide, and as much as 4 mm. thick, ovate, densely silveryto tawnyvillous, strongly nerved but the nerves obscured by the pubescence; first glume clasping, two thirds to nearly as long as the spikelet, sparsely villous or glabrescent toward the acuminate apex; second glume slightly longer and more pointed than the sterile lemma, both exceeding the fruit, the lemma inclosing a villous palea of equal length and a staminate flower; fruit 4.2-4.5 mm. long, about 1.6 mm. wide, the margins of the lemma clothed with long white hairs, otherwise smooth and shining.
Type; locality: Chile.
Distribution: Southern Arizona and California; also in Chile and Argentina.

Perennials, Terrestrial, not aquatic, Rhizomes present, Rhizome elongate, creeping, stems distant, Stolons or runners present, Stems nodes swollen or brittle, Stems erect or ascending, Stems solitary, Stems terete, round in cross section, or polygonal, Stems branching above base or distally at nodes, Stem nodes bearded or hairy, Plants conspicuously hairy, grayish, or wooly, Stem internodes hollow, Stems with inflorescence less than 1 m tall, Stems, culms, or scapes exceeding basal leaves, Leaves mostly cauline, Leaves conspicuously 2-ranked, distichous, Leaves sheathing at base, Leaf sheath mostly open, or loose, Leaf sheath hairy, hispid or prickly, Leaf sheath hairy at summit, throat, or collar, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades 2-10 mm wide, Leaf blades mostly flat, Leaf blade margins folded, i nvolute, or conduplicate, Leaf blades mostly glabrous, Leaf blades more or less hairy, Ligule present, Ligule a fringed, ciliate, or lobed membrane, Inflorescence terminal, Inflorescence an open panicle, openly paniculate, branches spreading, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence branches more than 10 to numerous, Flowers bisexual, Spikelets pedicellate, Spikelets dorsally compressed or terete, Spikelet less than 3 mm wide, Spikelets with 1 fertile floret, Spikelets with 2 florets, Spikelet with 1 fertile floret and 1-2 sterile florets, Spikelets solitary at rachis nodes, Spikelets all alike and fertille, Spikelets bisexual, Spikelets disarticulating below the glumes, Spikelets conspicuously hairy , Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes distinctly unequal, Glumes equal to or longer than adjacent lemma, Glume equal to or longer than spikelet, Glume surf ace hairy, villous or pilose, Glumes 4-7 nerved, Lemma similar in texture to glumes, Lemma becoming indurate, enclosing palea and caryopsis, Lemma 5-7 nerved, Lemma 8-15 nerved, Lemma glabrous, Lemma body or surface hairy, Lemma apex acute or acuminate, Lemma awnless, Lemma margins inrolled, tightly covering palea and caryopsis, Lemma straight, Palea present, well developed, Palea about equal to lemma, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis, Caryopsis ellipsoid, longitudinally grooved, hilum long-linear.

Panicum urvilleanum is a species of grass known by the common names desert panicgrass and silky panicgrass. It is native to the southwestern United States and northern Mexico, where it grows in sandy habitat, including the dunes of the deserts. It is also known in parts of South America.

This is a stoloniferous perennial grass growing up to a meter tall with hairy leaves up to 45 centimeters long. The inflorescence is a branching, spreading panicle up to 35 centimeters long bearing oval-shaped spikelets coated in downy white or silvery hairs.