Allelopathic Effects of Osmunda cinnamomea on Three Species of Dryopteris

Abstract

Plants can reduce competition for limited resources by chemically inhibiting the growth and development of other species (allelopathy). In moist environments, the inhibitory chemicals are leached from growing or senescent leaves by rainfall, are exuded from the roots, or result from decomposition of the plant (Rice, 1984). Most studies of allelopathy in pteridophytes have focused on the effect of fern species on angiosperms. For example, Gliessman & Muller (1978) found in southern California meadows that toxins from Pteridium aquilinum severely affected some species of herbs and annual grasses while not affecting or only slightly affecting others. Of the few investigations of allelopathy among fern species, even fewer have focused on species which are found in the same general habitat. Two studies involving species found in the same general habitat investigated chemical interactions at the gametophyte stage of the life cycle. Bell (1958) found that various extracts of prothalli from Dryopteris filix-mas inhibited germination or reduced growth in D. borreri gametophytes; Petersen & Fairbrothers (1980) found that gametophytes of Osmunda cinnamomea reduced growth in Dryopteris intermedia gametophytes and that D. intermedia gametophytes reduced growth in 0. cinnamomea gametophytes. Other studies of species found in the same general habitat looked at the effect of the sporophyte on the gametophyte stage of the life cycle. Bell & Klickoff (1979) discovered that sporophytes of Polystichum acrosticoides, Polypodium vulgare, and Onoclea sensibilis reduced gametophyte growth for all species but P. vulgare. Munther & Fairbrothers (1980) found autotoxic as well as allelopathic inhibition of spore germination from sporophytes of Osmunda cinnamomea, 0. claytonia (no allelopathic effects), and Dennstaedtia punctilobula. All of the species used in these studies, although found in the same general habitat, do not generally occur in close proximity. This paper reports on an experiment performed to determine the allelopathic effect of sporophytes of Osmunda cinnamomea on the number and growth rate of gametophytes of Dryopteris carthusiana, D. cristata, and D. goldiana. 0. cinnamomea grows in close proximity with D. carthusiana and D. cristata but not with D. goldiana. 0. cinnamomea is, however, found in the same general habitat as D. goldiana. Both of the experiments with 0. cinnamomea mentioned above showed allelopathic effects on Dryopteris and other species (Munther & Fairbrothers, 1980; Petersen & Fairbrothers, 1980). Cinnamic acid and benzoic acid derivatives, which have been implicated as allelopathic agents in a number of studies (Rice, 1984), have been found in 0. cinnamomea (Bohm & Tryon, 1967).