Ascocarps in vertical section initially subepidermal, epidermal cells may become filled with fungal tissue as ascocarps mature, but extent to which this occurs varies, and in some collections ascocarps remain completely subepidermal. Upper ascocarp wall up to 50 µm wide, narrower toward s outside edge of ascocarp, comprising brown to pale brown, angular cells, with an area of dark brown to black cells near ascocarp opening. Exposed face of broken upper wall lined with 15-30 µm wide layer of hyaline, cylindric cells. Upper wall may contain cells from partially disrupted fibre bundles of leaf. Lower wall up to 15 µm wide, of brown, thick-walled, 4-6 µm diam. cells.

Paraphyses 1.5-2 µm diam., apex undifferentiated or circinate, extending 10-15 µm beyond asci. Asci 65-105 x 8-10 µm, subclavate, tapering to small, rounded apex, wall unthickened, 8-spored. Ascospores 30-65 x 1.5-2 µm, with well developed gelatinous sheath.

CHARACTERISNCS IN CULTURE: Ascospores from PDD 45304 and PDD 49360 germinated on agar plates after 48 hours. On OA colonies 8 cm diam. after 5 weeks, agar vinaceous-brown, aerial mycelium sparse, cottony, white to pale grey. Dark, globose structures developing near centre of colonies, remaining sterile.

NOTES: Ascocarp structure is similar in L. gramineum and L. rubrum, the two Lophodermium species found on grasses in New Zealand. The ascocarps are initially subepidermal, the upper wall is wider near the ascocarp opening, and is composed mostly of pale brown cells, with a restricted group of darker, thicker walled cells close to the ascocarp opening. The opening itself is lined with a well developed layer of pale, thin-walled, cylindric cells. The same ascocarp structure is also seen in most of the Lophodermium spp. from grasses considered by Tehon (1935).

Cannon & Minter (1986) reported L. gramineum from India. They also examined isotype material and described the asci as 12-15 µm wide, which is wider than in the New Zealand collections. In most Lophodermium species ascus width is a fairly stable character, and the New Zealand collections may represent a different species. However, the taxonomy of monocotyledon-inhabiting Lophodermium species is confused. The New Zealand collections are retained in L. gramineum since they fit this species as circumscribed by Tehon (1935), and they are indistinguishable from an Australian collection referred to this species by Walker (1980).

Two collections on Carex (PDD 46148, 48259) are the same as L. gramineum in macroscopic appearance and in vertical section, but differ in ascus length (120-165 µm) and ascospore length (60-85 µm). Because all specimens from New Zealand which are accepted in L. gramineum are on Gramineae, it may be best to recognize the fungus on Carex as a distinct species, but uncertainty in the taxonomy of Lophodermium from these plants means that its affinities remain uncertain.

See also notes under L. rubrum.