THE EFFECT OF TEMPERATURE AND PHOTOPERIOD ON THE DEVELOPMENT OF GEOGRAPHICALLY ISOLATED POPULATIONS OF FUNARIA HYGROMETRICA AND WEISSIA CONTROVERSA

Geographically isolated populations of Funaria hygrometrica Hedw. and Weissia controversa Hedw. were cultured under controlled axenic conditions in the laboratory to determine the developmental variability found between and within two species of widespread distribution. Funaria plants were found to grow more rapidly than those of Weissia; the latter could not be induced to complete the life cycle in culture, and generally had a less broad tolerance to environmental extremes than did Funaria. Optimum temperatures of 30 C for spore germination and 25 C for protonematal growth and gametophore formation were observed in all populations of Funaria. Gametangial formation required cooler temperatures in all populations; however, optimal temperature requirements and sporophytic growth characteristics were population-dependent. The temperature responses of the various stages of the life cycle correlate well with seasonal temperature fluctuations that might be expected in nature. The presence of ecological races in Funaria hygrometrica is demonstrated in the behavior of the reproductive stages of the life cycle.