The long conidiophores of Cladosporium herbarum measure about 250 µm in length and 5 µm in diameter, they are more or less distinct from the hyphae (Figures 1 and 2). Simple or sympodial growing, they have a thickened end at the anchoring point of the conidial chains.
The conidia are ellipsoidal to cylindrical, the ends of which are rounded, and bear very characteristic brown scars (figure 3). Unicellular to multicellular (up to 4 cells), they then measure 5.5-13.0 x 3.8-6.0 µm. Let us add that the formed conidial chains easily dissociate to be carried by the wind.
Appearance of the colonies on malt-agar medium : they slowly develop into a velvety carpet of dark olive green color with black edges, becoming powdery when the abundant production of conidia takes place. The reverse side of the colony appears black.