Are produced singly (see photo immediately above), in aggregates, in an unorganized hyphal matrix, or in a highly ordered hyphal matrix (see photos at right), with layers of the spore wall usually continuous with a wall of the subtending hypha. They also may form within roots, possibly as a substitute or as a replacement for vesicle development in some species such as G. clarum and G. intraradices.
Develop on a cylindrical, flared, or constricted unspecialized fertile hypha. In most cases, spores are borne terminally, but some may form intercalarily (rare).
Partition contents from that of the subtending hypha by different structural mechanisms such as an amorphous plug, a septum, an inner sublayer of the laminate layer of the spore wall, or thickening of all sublayers of the laminate layer of the spore wall.
Form the greatest number of layers with the widest variety of phenotypes amongst the three families of Glomales. Only a few species do not have an evanescent mucilagenous outer layer (stains pink to red in Melzer's reagent) that is a major component of the juvenile spore and hyphal walls. All have a rigid layer with sublayers (or laminae) that is continuous with the subtending hyphal wall.
May synthesize a separable thin (and hence flexible) sublayer of the laminate layer of the spore wall which previously has been defined as a "membranous wall". However, it originates as part of the subtending hypha and remains attached in some broken spores, so it is not a separate wall.
Germinate usually by emergence of the germ tube through the lumen of the subtending hypha.