Neither layer reacts in Melzer's reagent. Closure by a plug concolorous with the wall of the sporogenous cell. Arbuscules with many fine tips from a swollen trunk. Hyphae often with knobs or projections, usually densely coiled near entry points. Auxiliary cells and external hyphae often amass around the root, with the former most abundant in pot cultures just prior to spore formation and declining thereafter.
External hyphae are brown.
Given the difficulty in crushing such large spores and the resultant jumble of flexible inner wall structures, such a conclusion is not surprising. We have had this fungus in culture for almost a decade and have mounted numerous spores to find some that gave a clear picture of germinal wall organization.