Ambispora leptoticha (glomoid morph)

Whole Spores

COLOR: White to pale yellow brown (0-5-30-0)

SHAPE: Globose, subglobose, with many spores irregular.

SIZE DISTRIBUTION: 60-260 µm

Subcellular Structure of Spores

SPORE WALL: Two layers (L1 and L2), often adherent but sometimes separating; both colorless in youth.

L1: Outer layer, hyaline to pale yellow (0-0-20-0), with a flaky surface to which bits of debris often are attached. It is this characteristic which often gives whole spores a “dirty” appearance and additional brown coloration. This layer tends to break down with age and thus often is of variable thickness, ranging usually from 2.4-4 µm. The surface of this layer also reacts in Melzer’s reagent, with the color ranging from a pale pink (0-15-20-0) to orange-red (0-60-60-0).

L2: A layer consisting of hyaline to subhyaline (0-0-10-0) sublayers (or laminae) that increase in number with thickness. The composite layer is 4-8 µm thick, and appears to have some resiliency when pressure is applied. Thus, as spores are broken, this layer may “flatten” or fold instead of breaking (especially in younger spores). The inner sublayers of L2 often appear wrinkled within minute folds because of this resiliency. Despite this appearance, there are no flexible inner walls present in mature spores.

Mycorrhizae

Arbuscules and hyphae in cortical cells of sorghum, sudangrass, corn and red clover roots stain with variable intensity in trypan blue, ranging from almost invisible, a pale blue (most common), to slightly dark blue. Hyphae often are coiled within individual cells, with similar dimensions (8-12 µm wide) inside and outside roots. Contrast in photos is digitally enhanced to better see mycorrhizal structures.