The character that mainly defines this group is the simultaneous production of the primary conidia, the ultrastructure of which has been studied for certain genera in chapter III.

In practice, Barron (1968) differentiated the ampulla of Botryoblas­ tosporae from certain swellings of Sympodulosporae:

— in the first case, the ampulla is produced before conidiogenesis; — in the Sympodulosporae, the bulging is the result of successive

conidiogenesis. Blastobotrys is a particular case studied by de Hoog (1974) and Cole

and Samson (1979). The conidiophore, which grows sympodially, produces ampullae, which are perhaps primary conidia, giving rise to

Botryoblastosporae 149 secondary conidia more or less simultaneously. The secondary conidia remain attached to the ampullae and are released along with them.