Callus Tissues from the Mosses Polytrichum and Atrichum.

Callus-like tissues, isolated from protonemal cultures of two species of mosses, grow vigorously and without marked differentiation on media containing sucrose, casamino acids, and coconut milk. On mineral agar and on media containing sorbitol the tissue from Polytrichum (found diploid) reverts to the growth pattern of apparently normal moss plants.