Bothriochloa alta
Bothriochloa edwardsiana
tall beardgrass, tall bluestem
Edwards Plateau beardgrass, Merrills 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.
35-65 cm, slender, stiffly erect, rarely geniculate;
lower nodes shortly hairy, hairs shorter than 3 mm, usually off-white and ascending;
upper nodes glabrous or glabrate.
cauline;
ligules 1-3 mm;
blades 20-30 cm long, 4-10 mm wide, glabrous or sparsely pilose near the base.
mostly basal, glaucous;
ligules 1-1.5 mm;
blades 10-25 cm long, 1-2(3.5) mm wide, flat to rolled, with 3-7 mm hairs below the middle.
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.
6-12 cm, loose, fan-shaped;
rachises shorter than 5 cm, with 3-6 branches;
branches longer than the rachises, not rebranched, with 1 rame;
rame internodes with 3-5 mm marginal hairs.
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 5-8 mm, lanceolate;
lower glumes 5.5-7 mm, glabrous, shiny, with a deep dorsal pit, tapering to a narrow, slightly bifid apex;
awns 20-28 mm;
anthers 0.5-1 mm.
spikelets 3.8-4.4 mm.
spikelets 2.5-3.5 mm, sterile.
= 120.
= 60.
Bothriochloa alta
Bothriochloa edwardsiana
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 edwardsiana grows in the rocky plains and prairies of the Edwards Plateau of Texas, on calcareous soil, at 300-600 m. It also grows in northern Mexico and Uruguay. It resembles B. hybrida in some respects, but that species has a more robust habit, predominantly cauline foliage, and wider leaf blades.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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