Colonies developing in living leaves, rather poorly delimited, extending to around 20 mm in length (i.e. ± parallel to the midrib) and 15 mm in width, the included leaf tissue becoming brown and necrotic by mid summer. Anamorph: conidiomata acervular, forming on leaf veins within the infected area, blackening the surrounding tissue, pulvinate, 200-350 µm in length and 50-100 µm in width; interapeidermal. Basal wall composed of a narrow layer of hyaline angular cells, the upper wall composed only of plant tissue and sloughing away to expose the conidia. Conidiophores absent, or present only as short cells subtending small tufts of conidiogenous cells. Conidiogenous cells 5-7 x ca 2 µm in size, proliferating percurrently. Conidia 6-7.5 x 2-3 µm, fusiform to elongate-ovoid, straight or slightly curved. Teleomorph: stromata absent. Ascomata perithecia, formed on overwintered dead leaves, 150-400 µm diam., globose to elongate, immersed in plant tissue and causing it to swell outwards, scattered or in small clusters over the entire lesion. Ascomatal neck long, straight, black, extending laterally from one side of the ascoma, measuring 250-400 µm in length and 40-50 µm in width. Ascomatal wall 6-8 µm thick, narrow and weakly pigmented, composed of two layers of flattened cells. Interascal tissue not present. Asci 60-80 x 6-7 µm, fusiform, with an refractive J- apical ring ca 1.5 µm in diam., 8-spores. Ascospores arranged in a fascicle, 40-65 µm in length, with one slightly submedian septum,with hair-like appendages at each end. The upper cell is slightly wider than the lower, 1.5-2 µm versus 0.7-1 µm below.