Plants superficial, ovate, pointed or umbonate, attached by a basal rhizomorph, becoming expanded when 2-3 cm. across. Exoperidium saccate, split to about the middle into 5-9 pliable, thin, expanded equal acute rays; fleshy layer brown, adnate, frequently rimose; exterior smooth, free from debris; base concave or plane, sometimes convex, with a prominent umbilical scar. Endoperidium sessile, to 15 mm. diameter, globose, glabrous, brown, partly enclosed by the saccate base of the exoperidium; peristome fibrillose, almost plane, concolorous or pallid, even, seated on a small depressed silky zone. Gleba umber; pseudo-columella indistinct. Spores globose, 3-3.5um diameter, epispore umber, 0.5um thick, finely and moderately verruculose. Opinions differ as to the characters of the species Fries named Geaster saccatus. I have followed modern European workers in considering it to be a plant with a fibrillose peristome, exoperidium externally free from debris, umbilical scar, and spores 3-3.5um diameter. Some workers have confused it with G.fimbriatum, others with G. triplex. Lloyd appeared to have had no clear conception as to the species; for some Australian collections named by him as G.saccatum proved to be G.triplex, G.australe and G.minus; one was correctly named, and a fifth, named by him as Geaster arenarius, I have placed under G.saccatum. His uncertainty apparently also confused Smith (1935) who found difficulty in separating the species from G.triplex, largely because he attempted delimitation on, the variable—and therefore unsuitable—feature of plant size.