20 Flora of the Palouse Region 



A alba L. Perennial with creeping rootstocks: culms erect, .5-1 m. tall: 

 leaf blades flat, usually scabrous, the sheaths smooth: panicle 7-20 cm. long, 

 open at first, then contracted, greenish or purple: palet present, one-third 

 to one-half the length of the flowering glume. Abundantly introduced. 



A. exarata Trin. Perennial, tufted, the culms 30-90 cm. tall: leaves erect, 

 the blades flat, 2-6 mm. broad, 5-10 cm. long, scabrous, the upper distant 

 from the panicle: panicle strict, pale green, spike-like or interrupted, the 

 short branches appressed and spikelet bearing to the very base. Common 

 in moist soil. 



A. SCOUleri Trin. Perennial with running rootstocks: culms slender, 

 erect, about 60 cm. tall: radical leaves numerous; those of the culm usually 

 2-3; the blades flat, 1-2 mm. broad, 7-10 cm. long, strongly scabrous; the 

 sheaths nearly smooth: panicle erect, narrow, purplish, 7-12 cm. long, the 

 branches scabrous, naked below. In moist soil, not common. 



A. SCabra Willd. Annual, tufted, 15-90 cm. tall: leaves flat or involute, 

 narrow, very scabrous: panicle very loose, 15-30 cm. long; branches in 

 whorls of 2-12, capillary, 5-15 cm. long, branched above the middle and 

 spikelet-bearing only near the tips. Common in both dry and moist places. 



32. CALAMAGROSTIS. 



Inflorescence paniculate: spikelets 1 -flowered, the pubescent ra- 

 chilla usually prolonged beyond the flower: empty glumes 

 keeled, membranous: flowering glume hyaline, shorter than the 

 empty ones, obtuse, bearing a straight, bent or twisted dorsal awn: 

 callus usually copiously long-hairy at the base or rarely the hairs 

 scant or short: palet shorter: grain free, enclosed in the flowering 

 glume. 



Awns geniculate, exserted: panicle usually pale. C. suksdorfii. 



Awns straight, included: panicle purple. C. macouniana. 



C. suksdorfii Vasey. Culms tufted, .6-1 m. tall: culm leaves 3-4, 2-4 mm. 

 wide: panicle usually narrow and dense, 8-12 cm. long, erect, commonly 

 pale green, the branches short and flower bearing to the base: spikelets 3-4 

 mm. long: flowering glume shorter than the empty ones, obtuse, 4-toothed 

 at apex, bearing a stout, nearly basal, geniculate awn, as long or longer than 

 itself. 



var. luxurians Kearney. Panicle larger, 10-20 cm. long, 2-3 cm. wide: 

 spikelets 4-5 mm. long. 



The most abundant grass in pine forests, the variety less common than the 

 typical form. 



C. macouniana Vasey. Culms 60-120 cm. high, erect, slender: leaf 

 blades narrow, flat, long-attenuate, 15-25 cm. long: panicle 10-12 mm. long, 

 purple, narrow or pyramidal, loose, the branches in fives, slender, naked 

 below: spikelets small, 2-2.5 mm. long: flowering glume equalling the empt)' 

 ones, 2 lobed at apex, bearing a very short straight awn from above the 

 middle of the back. Wet banks of the Palouse at Pullman, not common. 



33. HOLCUS. 



Panicles spike-like or open: spikelets deciduous, 2-flowered, the 

 lower flower perfect, the upper staminate: empty glumes mem- 



