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Reproductive Biology of Entodon cladorrhizans (Bryopsida, Entodontaceae). I. Reproductive Cycle and Frequency of Fertilization

1983; American Society of Plant Taxonomists; Volume: 8; Issue: 4 Linguagem: Inglês

10.2307/2418357

1548-2324

Lloyd R. Stark,

Lichen and fungal ecology

In central Pennsylvania, Entodon cladorrhizans is self-fertilizing and perigonia are initiated before on a given stem. Maturation of antheridia and archegonia overlap and the fertilization interval is ca. 5 weeks (mostly July); sporophytes mature 6 to 9 months later. Numbers of perigonia per stem are greater and more variable than for and the numbers of each are positively correlated along a stem. Some 90% of initiate sporophytes. Fre- quency of perichaetial fertilization is independent of the number of per stem. Three lines of evidence suggest that self-fertilization occurs: 1) frequency of fertilization is significantly higher on bisexual stems than on perichaetial stems, 2) unfertilized perichaetia tend to occur distal to perigonia of the same stem, and 3) stems with highest numbers of perigonia exhibit highest fertilization frequencies. Greene's (1960) notational system for record- ing phenological stages of gametangia and spo- rophytes has aided study of reproductive biol- ogy of mosses. Forman (1965) also produced a system especially useful for macroscopic ex- amination of many specimens. The classes rec- ognized are somewhat arbitrary but offer use- ful standards for comparing and contrasting sexual and sporophytic cycles in mosses. Sev- eral phenological studies have followed, per- haps most notable Longton and Greene's (1969) elucidation of the reproductive cycle of Pleu- rozium shreberi (Brid.) Mitt. Other recent works focusing on one or several species include Johnsen (1969), Clarke and Greene (1970, 1971), Hancock and Brassard (1974), Zehr (1979), and Longton (1979). Zander (1979) reviewed the use of sporophyte maturation dates in bryophyte systematics. My intent is to review the phe- nology and demography of sex organs, to ap- praise the frequency with which fertilization occurs, and to present evidence of self-fertil- ization in Entodon cladorrhizans (Hedw.) C. Muell., a member of Entodontaceae (Bryopsida) that is widely distributed throughout eastern North America. It can be distinguished from the six other species of Entodon occurring in its range by the autoicous sexual condition (with archegonia and antheridia in separate clusters on the same plant), complanate leaves, pres- ence of an annulus, papillose exostome, and nearly smooth endostome (Crum and Ander-