4. Lathyrus Myrtifòlius Muhl. Myrtle-Leaved Marsh Pea

Fig. 2627

Lathyrus myrtifolius Muhl.; Willd. Sp. Pl. 3: 1091. 1803. L. palustris var. myrtifolius A. Gray, Man. Ed. 2, 104. 1856. L. myrtifolius macranthus White, Bull Torr. Club 21: 448. 1894.

Perennial, usually quite glabrous sometimes pubescent; stems slender, angled, not winged, 1°-3° long, weak. Stipules obliquely ovate, or half-sagittate, 6"-12" long, often 4"-6" wide and toothed; leaflets 2-4 pairs, mostly 3 pairs, oval, oval-oblong or ovate, mucronate and acute or obtuse at the apex, narrowed at the base, 9"-2' long, 3"-7" wide, rather thin; tendrils branched, peduncles equalling the leaves, or shorter, 3-9-flowercd; flowers purple or purplish, similar to those of the preceding species; pod linear, glabrous, sessile, 1'-2 long, 3 1/2" wide or less.

In moist or wet grounds, New Brunswick to Manitoba, south to North Carolina and Tennessee. May-July.

5. Lathyrus Decaphýllus Pursh. Prairie Vetchling

Fig. 2628

L. decaphyllus Pursh, Fl. Am. Sept. 471. 1814. Lathyrus polymorphus Nutt. Gen. 2: 96. 1818.

Perennial, erect or ascending, glabrous, or finely pubescent, 6'-18' high. Stems angled; stipules half-sagittate, acuminate, 4"-12" long, 1"-3" wide; leaves petioled; leaflets 3-7 pairs, obtuse or acute and mu-cronulate at the apex, narrowed at the base, thick, conspicuously reticulated, 1'-2 1/2' long, 3"-8" wide; stipules when present branched, but often wanting; peduncles usually shorter than the leaves; flowers purple, 1'-1 1/2' long, showy; pod linear, stipi-tate; seeds with a narrow stalk and short hilum.

Kansas (?), Idaho and Colorado to Arizona and New Mexico. March-July. Everlasting-pea.

6. Lathyrus Ornàtus Nutt. Showy Vetchling

Fig. 2629

L ornatus Nutt.; T. & G FL N. A. 1: 277. 1838.

Closely resembling the preceding species, but generally lower, often less than 1° high, glabrous or nearly so. Stipules lanceolate or linear, 2"-10" long; leaflets narrow, linear or linear-oblong, acute and mucronate, 4" - 12" long, \"-2." wide; tendrils commonly wanting; flowers purple, showy, 1'-1 1/2' long; pod linear, stipitate; seeds with a broad stalk and long hilum.

Prairies and plains, Oklahoma to Kansas and South Dakota, west to Colorado, Wyoming and Utah. May-June.

Lathyrus incànus (Rydb. & Smith) Rydb. differs in being villous-pubescent. It ranges from western Nebraska to Utah and Wyoming.