Confirmation of a Hybrid Isoetes from New Jersey

Abstract

A number of interspecific hybrids in the genus have recently been confirmed (Taylor & Luebke, 1988; Brunton & Taylor, 1990; Britton & Brunton, 1992). engelmannii x lacustris was reported for the first time from New Jersey by Taylor in Montgomery & Fairbrothers (1992). The hybrid was initially identified from herbarium material; however, the authors agreed at the time that confirmation by chromosome counts was necessary. This paper confirms the identity of the hybrid by chromosome counts, provides details of the morphology and ecology, and designates a binomial. lacustris L. (I. macrospora Dur.) was discovered in Lake Wawayanda, Sussex County, New Jersey, by J. L. Edwards in 1937 (Chrysler & Edwards, 1947). This species is near its southern limit of geographical distribution in northern New Jersey, and was listed as endangered in the state by Fairbrothers & Hough (1973). The population has been observed by Montgomery since 1965. engelmannii A. Braun is common in lakes and ponds in northern New Jersey. It was first collected in Lake Wawayanda by J. L. Edwards and E. T. Wherry in 1938 (Taylor in Montgomery & Fairbrothers, 1992). Taylor recognized the hybrid by its irregular, polymorphic megaspores (Wagner et al., 1986) during examination of specimens for the New Jersey Ferns and Fern Allies. The parents were deduced from the spore surface ornamentation and the presence of the possible parents in the same lake. engelmannii x lacustris was first collected by J. L. Edwards and J. Dezer in 1937, and again by J. L. Edwards in 1938. Montgomery collected the hybrid with I. lacustris in 1965. All collections were labeled as Isoetes macrospora, the recognized name for North American L. lacustris, until Taylor's identification. METHODS