The Marchantiaceae of Sinsinawa Mound

Abstract

This family is represented by three species: Marchantia polymorpha, Conocephalurn conicumn, and Preissia commutata, all of which grow in abundance and fruit luxuriantly year after year in the locality of Sinsinawa Mound, Grant County, Wisconsin. The writer has been interested in observing and noting the seasons for the discharge of the spermatozoids, reduction division, and the subsequent development of the sporophyte and spore dissemination in each of the three species. All three plants are found in great profusion on the north side of a rockbound, spring creek, Marchantia polynorpha on the lower level, just at the water's edge, and, in the rainy weather, sometimes almost submerged; while Concephalumr conicumn and Preissia commut(dta are often very closely associated in dense mats a little higher up on the rocky bank. Preissia commutata is also found far away from water, fruiting most luxuuriantly on quite dry rocks. 'The spermatozoids of Marchantia polymnorpha are often ready for dispersal about May first. However, there is some variation in all of the activities of this plant. This is due not only to differences in the seasons but also to differences in the individual plants. The variations in the time of fertilization are easily noted in Marchantia polymorpha by the unevenness in the elongation of the stalks of the archegonial heads as these stalks begin to lengthen only after fertilization has occurred. The formation of the tetrads occurs as early as June fifteenth and the spores are ripe about the first of July. It is quite possible sometimes to collect plants that are much less mature at this time. In Conocephaltm conicum, the spermatozoids are discharged about June fifteenth and there is considerable uniformity in