Bothriochloa alta
Bothriochloa laguroides
tall beardgrass, tall bluestem
silver beardgrass, silver bluestem
1.3-2.5 m tall, 2-4 mm wide, stiffly erect, not or only sparingly branched;
nodes hirsute, hairs 2-6 mm, stiff, spreading, tan;
internodes glaucous below the nodes.
35-115(130) cm tall, usually less than 2 mm thick, erect or geniculate at the base, branched at maturity;
nodes shortly hirsute, pilose with erect hairs, or glabrous.
cauline;
ligules 1-3 mm;
blades 20-30 cm long, 4-10 mm wide, glabrous or sparsely pilose near the base.
usually basal (sometimes cauline on robust plants), usually glaucous;
ligules 1-3 mm;
blades 5-25 cm long, 2-7 mm wide, flat to folded, mostly glabrous.
14-25 cm long on the larger shoots, 3-6 cm wide when pressed, oblong, dense;
rachises 10-20 cm, with numerous branches, rachises and branches kinked and wavy at the base from being compressed in the sheath;
branches 2-8 cm, much shorter than the rachises, erect to appressed, with multiple rames;
rame internodes villous on the margins, with 5-8 mm distal hairs.
4-12(14) cm, narrowly oblong or lanceolate, silvery-white or light tan;
rachises 4-8 cm, with more than 10 branches;
branches 1-5.5 cm, erect-appressed, rarely with axillary pulvini, lower branches shorter than the rachises, usually with more than 1 rame;
rame internodes with a groove wider than the margins, margins copiously hairy, hairs 3-9 mm, at least somewhat obscuring the spikelets.
spikelets 4.5-6 mm, ovate;
lower glumes shortly pilose, with or without a dorsal pit;
awns 18-22 mm;
anthers about 1 mm, often remaining in the floret, light brown.
spikelets 2.5-4.5 mm, ovate, somewhat glaucous, apices blunt;
lower glumes glabrous or hirtellous, rarely with a dorsal pit;
awns 8-16 mm;
anthers 0.6-1.4 mm.
spikelets 3.8-4.4 mm.
spikelets 1.5-2.5(3.5) mm, shorter than the sessile spikelets, sterile.
= 120.
= 60.
Bothriochloa alta
Bothriochloa laguroides
Bothriochloa alta grows along roads, drainage ways, and gravelly slopes in the desert grasslands of the south-western United States, at 600-1200 m, and extends south to Bolivia and Argentina. It is not a common species in the Flora region. It often grows with and is mistaken for B. barbinodis, but differs from that species in having longer culms, panicles, and nodal hairs, and 2n = 120. Plants in the southwestern United States have larger spikelets and more hairy panicles than those of central Mexico, where the species was originally described.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Bothriochloa laguroides grows in well-drained soils of grasslands, prairies, roadsides, river bottoms, and woodlands, often on limestone, usually at 20-2100 m. Plants from the United States and northern Mexico belong to B. laguroides subsp. torreyana (Steud.) Allred & Gould, which differs from B. laguroides (DC.) Herter subsp. laguroides in its glabrous, or almost glabrous, nodes, long internode hairs, and pilose throat region. Occasional plants are found with spreading branches and axillary pulvini; they do not merit formal recognition. Bothriochloa laguroides subsp. torreyana is used in landscaping. It does well on rocky slopes and sandy banks.
Bothriochloa laguroides has been confused with B. saccharoides (Sw.) Rydb., a more southern species that differs from B. laguroides in having pilose leaves, a narrow central groove in the internodes and pedicels, and panicle branches with axillary pulvini.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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