Colonies dark greenish to black, black in reverse, and relatively slow-growing. The dark spores are 1- or 2-celled and occur in long, branching chains that arise from a dark conidiophore. The youngest spore is at the top of the chain. The slightest movement will disrupt the chains, making microscope mounts of the whole structure nearly impossible. The best way to recognize the genus is by the prominent scars on the spores where the adjacent ones were attached. Very common on decaying plants; the fungus most commonly isolated from air, both indoors and outdoors.
Species of Cladosporium are still not well worked out taxonomically. Most isolates from air and from habitats associated with humans have been referred to one of three species, separable by the following key:
1. Spores usually ellipsoidal in shape, only rarely spherical - 2
1. Spores often nearly spherical - C. sphaerospermum
2. Spores smooth - C. cladosporioides
2. Spores warty - C. herbarum
Holomorph: Mycosphaerella. Ref: Ellis 1971, 1976; de Vries 1952; Wang, 1990