io8 Flora of the Palouse Region 



V. americana Muhl. Perennial, stout or slender, 30-100 cm. high, nearly 

 glabrous: leaflets 4-8 pairs, very variable, usually elliptic or ovate, frequently 

 linear, acute, obtuse or truncate, mucronulate, entire or toothed above, 

 glabrous above, minutely puberulent beneath, about 2 cm. long; tendrils 

 well developed; stipules deeply toothed: peduncles usually shorter than the 

 leaves, 4-8-flowered: flowers purple-violet, 15-20 mm. long, short-pedicelled: 

 calyx-tube campanulate with short broad unequal teeth, somewhat pubes- 

 cent: pods glabrous, 2-4 cm. long, 6-8 mm. broad. Common in copses. 



175. LATHYRUS. 



Mostly smooth perennial herbaceous vines, rarely erect herbs: 

 leaves pinnate, mostly tendril-bearing: flowers in racemes or 

 sometimes solitary; peduncles usually equalling or exceeding the 

 leaves and several-flowered: calyx-teeth nearly equal or the upper 

 ones somewhat shorter than the lower: corolla rather larger than 

 in Vicia: stamens diadelphous or monadelphous below: style dor- 

 sally flattened near the top, hairy on the upper side; ovules gen- 

 erally numerous: pod flat or terete, 2-valved. 



Leaflets 3-6 pairs, with tendrils. L. parvifolius. 

 Leaflets 1-2 pairs, without tendrils. 



Flowers white, 1.5 cm. long. L. nevadensis. 



Flowers purple, 1 cm. long. L. bijugaTus. 



L. parvifolius Wats. (L. pauciflorus Fernald.) Glabrous throughout, 

 60-90 cm. high: stems angled: leaflets 3-6 pairs, oblong-elliptic, thickish, 

 prominently veined, paler beneath, acute and cuspidate, rounded at base, 2-4 

 cm. long; stipules about half as long as the adjacent leaflets; tendrils sim- 

 ple or branched: peduncles exceeding the leaves, 3-5-flowered: flowers vio- 

 let, about 2 cm. long: calyx-teeth slightly pubescent, about as long as the 

 tube: pods smooth, 4-6 cm. long. Bluffs of Snake River. 



var. tenuior Piper, n. var. Leaflets linear or linear-lanceolate, 3-6 cm. 

 long, otherwise as in the species. The type is Elmer no. 52, from the Snake 

 River Bluffs near Almota. It also occurs on Union Flat. 



L. nevadensis Wats. Erect or decumbent, 12-25 cm - high: leaflets 1-2 

 pairs, elliptic or ovate, obtuse, cuspidate, thinly pubescent and paler be- 

 neath, 2-4 cm. long; stipules narrow, acuminate; tendrils none: peduncles 

 exceeding the leaves, 2-4-flowered: flowers stout-pedicelled, white or och- 

 roleucous, nearly 2 cm. long: calyx-teeth triangular-acute, shorter than the 

 tube. Near Troy, Idaho. 



L. bijugatus White. Erect, 10-15 cm - high, glabrous or sparsely pub- 

 escent: stems not winged: leaflets 1-2 pairs, oblong or elliptic, acute, cuspi- 

 date, about 2 cm. long; stipules sagittate, narrow, 5-10 mm. long; tendrils 

 none, but the rachis prolonged into a slender tip: peduncles shorter than 

 the leaves, 1-4-flowered: calyx-teeth triangular, acute, about as long as the 

 tube: corolla purple, 8-10 mm. long. 



var. sandbergii White. Leaflets linear or linear-lanceolate, 4-6 cm. long. 

 The species and the variety occur together on stony hillsides. 



