MORPHOLOGY OF THE URBAN MOSS, TORTULA PAGORUM IN STERILE CULTURE

Abstract

  In sterile culture the protonemata of Tortula pagorum display three growth-forms that differ with respect to orientation of filaments, dominant cell shape, branching, and color. They were designated as: multidirectional, unidirectional, and stunted protonemata. Only stunted protonemata were found in natural collections. Shoots displayed six growth-forms in culture that differed with respect to dominant leaf type, leaf spacing, stem height, and occurrence and position of gemmae or brood-leaves. The first four growth-forms were found in culture and nature, and the last two in culture only. The development of each growth-form of the gametophyte from gemmae in culture was correlated with particular light, temperature, and substrate conditions. Gemmiferous shoots developed in culture at or under a wide range of light intensities, several photoperiod-temperature regimes, red light, temperatures from 15 to 26℃, pH values from 3.5 to 8.0, and also when high levels of salts, carbohydrates, or crude mixtures of particulate pollutants were added to the culture medium. The behavior of the gametophyte of Tortula pagorum helps explain the tolerance of this species to the special conditions of the urban habitat.