74164 Nerisyrenia canporum (Gray) Greene Fis. white. Some [illegible] [5] normal. Sparse in roadside [6] gravel. 2 mi. S. of Ocampo Coahuila. Oct 12, 1974 74165 Nerisyrenia sicava Roll. Fis. white, leaves entire, sicavea, abundant along roadside, Nef Hwy 30, 4 mi. [5] S of Cuatros Cienegas, growing n=10 near 74166 but readily destroyed or various habit & leaves. Coahuila gypsum flat Oct 12, 1974 74166 Nerisyrenia castillonii Roll. Perennial; Fis. white to lavender. Plants not hemispherical as in N. sicava. Leaves greenish, shallowly toothed & acute. Roadside, Nef Hwy 30, 4 mi. [10] S of Cuatros Cienegas. Gypsum n=18 flat. Growing with 74165. Coahuila. Leaves fleshy. There is no evidence of hybridization between us. 74165 r Oct 12, 1974 74166