The Appalachian Firmoss, a New Species in the Huperzia selago (Lycopodiaceae) Complex in Eastern North America, with a New Combination for the Western Firmoss

Abstract

The gemmiferous firmosses, containing the type species of Huperzia, Huperzia selago, are distinguished from the other members of Huperzia by concave-sided spores and specialized lateral branches consisting of gemmiphores and detachable gemmae. The species of the group hybridize and the hybrids possess abortive spores with spore fragments and undivided spore mother cells. In the past the systematic treatment of the species in this group has been unsatisfactory because no one has recognized the intermediate sterile hybrids. These can reproduce vegetatively by gemmae, often forming large populations. Undetected hybrid taxa muddle species boundaries by obscuring and combining the already subtle characters that differentiate species. The obviously abortive-spored hybrids have remained undetected by most botanists. Careful field study of sympatric populations of species and hybrids over the range of the taxa, as well as examination of over 6000 herbarium specimens, has resulted in the present alignment of species boundaries and the recognition of a new species, Huperzia appalachiana, in eastern North America. First, we will review the range and characters of the common firmoss species, and then present the range and characters of Huperzia appalachiana. Looking at the three major areas of overlap (the northern Appalachians, the southern Appalachians, and the north shore of Lake Superior), the consistency of characters will be examined as well as of hybrids. The shining firmoss, Huperzia lucidula, is an eastern North American endemic of moist conifer and deciduous forests and swamps, always with some shade. Common in the northern and eastern parts of its range, it extends north of the Great Lakes up into the boreal forest, south in the Appalachians to Georgia and Alabama, west in shaded moist sandstone ravines of Missouri and Arkansas and to the edge of the deciduous woods in Minnesota. It is a robust plant of indeterminate growth habit; the individual stems continue growing indefinitely, becoming decumbent with age and eventually rotting away at their base. The leaves are in annual zones of longer leaves and shorter leaves. The shortest leaves are bud leaves produced at the end of the growing season in the form of winter bud. In H. lucidula, the leaves of the two portions are similar in size and reflexed position. The long leaves are widest beyond the middle with serrate margins and, importantly, have no stomates on the upper surface. The gemmiphores and the gemmae are relatively large. The lateral lobes of the gemmae are broadly obtuse with an apiculate tip. The spores are relatively small, averaging about 25 gm.