Gaeumannomyces graminis  

Mycelium: with hyphae 4-7 µm wide, often in strands of 3-4 or more, hyphopodia either simple 7-15 x 4-7 µm (often many united as sclerotic masses) or lobed and terminal on side branches 15-25(-30) x 10-20(-25) µm, each has a clear dot at the point of host penetration.

Anamorph: Cadophora sp. Conidiogenous cells 9-18 x 2-3 µm. Conidia 4-7 x 1-1.5 µm, slightly to strongly curved, some semicircular.

Teleomorph: Ascomata (150-)200-400 µm diam., neck variable but usually 100-400 µm long and 70-100 µm diam, immersed. Peridium 25-40 µm thick, of 6-10 layers of compressed cells, indvidual cells 7-15 x 2-6 µm. Interascal tissue of paraphyses (when present) exceeding the asci, 8-10 µm diam at the base, tapering to 2-3 µm, often constricted at the septa. Asci 80-130 x 10-15 µm, elongate-clavate, apical ring small but distinct and seen as 2 refractive dots in side view. Ascospores (70-)80-105(-110) x 2-3(-4) µm, filiform with rounded ends, tapering more towards the base, slightly curved, hyaline to faintly tinged yellowish, 3- to 5-septate (later more), septa often indistinct.