CYPERACEAE

CYPERACEAE View in CoL View at ENA

RHYNCHOSPORA : Rhynchospora vernalis ( Cyperaceae ), a new species from peninsular Florida Primary authors:Edwin L. Bridges and Steve L. Orzell

Around 30 years ago, we first noticed a confusing Rhynchospora in central peninsular Florida. When using bristle characters, it keyed to Rhynchospora decurrens Chapm. , but it lacked the decurrent tubercle base of that species, and also differed in spikelet color, inflorescence shape, and habitat. We distributed five collections of this entity to herbaria labeled as R. decurrens before realizing it only superficially resembled that species. At that time, Rhynchospora sect. Mixtae Kük. (sensu McMillan 2007) was not well studied, with some species (such as R. sulcata Gale ) not consistently recognized until the detailed work on Rhynchospora in South Carolina by McMillan (2006, 2007). Although Florida material was outside of the scope of his study, the detailed descriptions, comparative character tables, illustrations, and discussion of variation in McMillan (2007), convinced us that our peninsular Florida entity did not match any of the known species in sect. Mixtae, and consequently, we here name R. vernalis as a new species.

Rhynchospora vernalis is named for its typically early spring peak flowering and fruiting, often with mature achenes by April or May in central Florida, when it is most conspicuous. This robust, clump-forming perennial species will occasionally reflower later in the season, but it typically has mature fruit long before most species of Rhynchospora in undisturbed habitats. It is distinguished from other species of Rhynchospora sect. Mixtae with some difficulty.Superficially, it might be mistaken for Rhynchospora mixta Britton , R. elliottii A.Gray , or R. microcarpa Baldwin ex A. Gray. The new species R.vernalis has a much more spreading inflorescence of lighter brown colored spikelets than R. microcarpa , and forms larger clumps of stiffer culms than does R. mixta . It tends to differ in habitat from either of these species, being locally abundant in deep wet prairies, shallow marshy, depressional ponds, and in the grassy groundcover of open cypress dome swamps. In these habitats, it is often in association with R. inundata Fernald and R. cephalantha A. Gray , and less commonly with R. fascicularis Vahl , R. filifolia A. Gray , R. rariflora Elliott , R. latifolia Baldwin ex Elliott , and R. tracyi Britton , none of which are closely related. It will key incompletely to R. sulcata or R. microcarpa in McMillan (2007) and to these or R. decurrens in most other keys to southeastern US Rhynchospora , but differs in several characters from each of these, as detailed in the description and key. It is rather common and widespread in central peninsular Florida, becoming less frequent north and south of this region.