Marchantia inflexa is a dioecious, thallose bryophyte that exhibits both sexual and asexual modes of reproduction. Sexual reproduction results in the production of spores, while asexual reproduction results in the production of asexual propagules, gemmae. This experiment compared the differences in early life history of spores and gemma under two different light treatments. Spores were collected from 4 mothers that were fertilized with up to 4 fathers and germinated in either a 45% or 37% light environment. Upon germination, 100 sporelings from each light treatment were transferred to pots filled with steamed soil and placed in the same light conditions as they were germinated. Simultaneously, 6-8 male and female genotypes were randomly chosen to collect gemmae to make sex-specific mixtures of gemmae. One hundred male and one hundred female gemmae were individually planted and evenly divided among the light treatments. Thrice weekly we recorded the life-history characters of time to first meristem split and first cup production. In bi-weekly censuses, we recorded cup number and photographs were taken to assess size. A repeated measures analysis of plant size revealed that the pattern of growth was affected by propagule type, light and the interaction of propagules and light. Gemmae plants were significantly larger at early dates, but there was no significant difference in size by the final census. Similarly, a MANOVA revealed significant effects of propagule type, light and the interaction of propagules and light on life-history traits on the final census date. Gemmae plants reached first meristem split earlier than spore plants, but spore plants began producing cups earlier and had more cups per unit area than gemma plants. These experimental results suggest that environmental conditions could influence the relative success of sexual and asexual reproduction under field conditions.

Key words: asexual reproduction, bryophyte, Life-history, Marchantia inflexa