sand bluestem
Andropogon hallii Hackel

click thumbnail to see a larger image

plantinflorescencespikeletillustration

Sand bluestem is very similar to and can hybridize with big bluestem (Andropogon gerardii). The foliage of sand bluestem is more gray and waxy than that of big bluestem, and sand bluestem also has much more prominent rhizomes and is more drought tolerant than big bluestem. The densely hairy joints of the branches of the linear branches of the flowering heads (rames) also distinguish this species from big bluestem. Sand bluestem is found in dry, sandy soils from northern Mexico into the central plains, where it is an important member of sand-hill prairie communities. This species mainly occurs farther west than Iowa, but it is also found in Illinois and Indiana. In Iowa, sand bluestem is very uncommon, having been recorded in only a few collections in Muscatine and Louisa counties. Pohl (1966) considered these to be accidental introductions, and the persistence of this species in southeastern Iowa is unconfirmed. The Flora of North America, however, reports it from the northern Loess hills as well as one location in central Iowa, and the occurrence of sand bluestem in western Iowa is likely to represent part of its native range.

Etymology: Andropogon from the Greek andros = man and pogon = beard, as the hairy spikelets characteristic of this genus are said to resemble a man’s beard. The specific epithet hallii is given in honor of Elihu Hall (1822-1882), an American botanist and explorer.

 

Plants strongly rhizomatous; rhizomes scaly, with internodes often longer than 2 cm. Culms 40-115 (-150) cm tall, strongly bluish-white. Leaves with the sheaths open, keeled slightly if at all, smooth; ligules fringed membranes 2-3 mm long; blades 23-30 cm long, 2-7 mm wide, with prominent midribs on the upper surface, often with some long hairs on the upper surface near the base of the blade. Flowering heads 4-9 cm long, 1.5-3 cm wide, of 2-3 rames, usually only terminal. Rames 3.5-8 cm long, exserted at maturity; internodes usually densely pubescent, hairs 3-5 mm long, often yellowish. Sessile spikelets 8-11 mm long; glumes nearly equal in size; lower glumes often scabrous to ciliate; awns absent or to 7.5 mm long. Pedicellate spikelets usually well developed and staminate, often as long as the sessile spikelets. Chromosome number usually 2n = 60, sometimes 70 or 80.

 

home - common name index - scientific name index - database - picture key - weedy grasses - ornamental grasses - Ada Hayden Herbarium - ISU