Growing in horse manure heavy with straw. Stem fragile, split easily. From: http://www.svims.ca/council/Coprin.htm - Coprinopsis nivea (Pers.) Redhead, Vilgalys & Moncalvo CAP 1.5-4cm across, 2-3.5cm high, somewhat cylindric then conic-bellshaped, later flattened with margin curved up or down; completely covered at first with snow-white, powdery to hairy-floccose veil, cap center often cream to pale ochraceous, toward margin becoming grayish and striate; flesh thin thin and membranous. GILLS free or adnexed, broad, white becoming black, edge white-fringed. STEM 5-12 cm x 0.2-0.8 cm, widening slightly downwards with base somewhat thickened, hollow, fragile, white-mealy on a whitish background. HABITAT single or a few together; on dung of horses and cattle. SPORE DEPOSIT very dark brown to black. MICROSTRUCTURES spores 12-19.0 x 10-15 x 7.5-11 um, lemon-shaped in face view, elliptic in side view; basidia 4-spored. basidia 4-spored, 25-40 x 12-16 um, surrounded by 5-7(8) pseudoparaphyses; pleurocystidia abundant, 50-150 x 25-65 um, ovoid to ellipsoid or vesiculose, cheilocystidia 30-80 x 15-50 um, similar to pleurocystidia; veil made up of nearly spherical elements 28 to 100 um wide; clamp connections sparse, probably just pseudoclamps REMARKS Coprinopsis nivea is characterized by the very large spores which are lemon-shaped in face view and elliptic in side view. Other features include its snow-white color due to a mealy-powdery veil (composed of spherocysts) that can be wiped off, white gills that turn black, slender white stem, and growth on cow patties and horse manure.