Vegetative cells are slender, needle-shaped rods with tapered
ends, 0.7 3–11 lm. Swarm colonies with fine radial
veins in a tough slime sheet. Sporangioles spherical or ellipsoidal,
relatively small, 20–70 20–50 lm, dull grayish
to dark yellow-brown and red-brown, with a definite wall,
0.5–1 lm thick, arranged in flat sori up to 500 lm wide
within a thin colorless slime layer, often also piled up, sometimes
forming branched tree-like structures; when tightly