Paraphyses similar to L. gramineum. Asci 120-165 x 9.5-10.5 µm, subclavate, tapering to small, rounded apex, 8-spored. Ascospores 61-84 x 1.5-2.5 µm, 0-1 septate, with well-developed gelatinous sheath.

CHARACTERISTICS IN CULTURE: Ascospores germinated on agar within 48 hours. On OA colonies 4 cm diam. after 3 weeks, aerial mycelium low, felted, bright orange-red in colour, agar surface orange-brown, remaining sterile.

ETYMOLOGY: rubrum = red; refers to colour of vegetative mycelium in the host tissue, and in culture.

NOTES: Distinguished from L. gramineum by colour of vegetative mycelium and by ascus and ascospore size. The pale, thin-walled cells lining the ascocarp opening become dark brown in colour in older ascocarps of L. rubrum, a feature not seen in L. gramineum.