Monographs Details: Nostoc willei
Authority: Gardner, Nathaniel L. 1927. New Myxophyceae from Porto Rico. Mem. New York Bot. Gard. 7: 1-144. pl. 1-23.
Description:Species Description - Thallus iregular in shape and size, firm, gelatinous, 1-4 mm. diam.; trichomes moderately contorted; cells cylindrical to slightly dolioform, 3.7-4 µ diam., slightly constricted at the dissepiments, up to 18 µ long, densely and finely granular; heterocysts spherical, 5-5.5 µ diam., smooth and hyaline; teguments hyaline; resting spores subcylindrical to ellipsoidal, 14-20 µ long, 7-9 µ broad, with a smooth hyaline membrane
Distribution and Ecology - Growing among moss on trunks of trees at Coamo Springs, no. 267, type.
Discussion:This species of Nostoc belongs to the Humifusa section of the genus created by Bornet and Flahault and is" related in the trichome characters to N. ellipse spo rum (Desm.) Rab.