Ascocarp development in Lophodermium nitens

Abstract

Ascocarps of L. nitens Darker develop in the spring on fallen needles of Pinus strobus L. The ascocarp initial is a compact stroma located between host epidermis and cuticle. Most of this stroma becomes elevated to form the clypeus, while the portion remaining in contact with the epidermis constitutes the incipient hypothecium. As the latter develops, paraphyses originate from the superficial hypothecial cells. Ascogenous elements arise from the bases of certain paraphyses. Occasionally, a paraphysis may give rise directly to an ascus but more frequently to a limited system of ascogenous elements. A number of such systems, similarly produced at various points over the whole hypothecial surface, collectively comprise the hymenium. Any given ascogenous system contains many nuclear pairs. The latter are interpreted as dikaryons because they occur in association with croziers and nuclear quartets, both of which are indicative of conjugate division.