Systematics Section / ASPT
Bone, Tiffany S. , Downie, Stephen R. , Affolter, James M. .
A phylogenetic study of the genus Lilaeopsis (Apiaceae).
The genus Lilaeopsis (tribe Oenantheae, family Apiaceae) consists of small, rhizomatous perennial herbs occupying moist or truly aquatic habitats. Fourteen species and four infrageneric taxa are recognized, and these are distributed primarily in North America, South America and Australasia. Lilaeopsis schaffneriana var. recurva (known only from southeastern Arizona and adjacent Sonoran Mexico) is federally endangered. The genus is extremely difficult taxonomically, as a result of its greatly simplified and generally similar vegetative morphology. In many species, the leaves are linear, hollow, and transversely septate, being derived from the rachis of a compound leaf. In addition, the size and shape of the leaves are readily modified in response to various degrees of submergence and light intensity, and features of the fruit are too uniform to be taxonomically useful. Molecular data are therefore essential to infer phylogeny. We are examining DNA sequence data to resolve relationships within the genus and to ascertain its position within the tribe. To date, we have procured nuclear rDNA ITS data from 50 accessions representing most taxa; additional data from the chloroplast rps16 intron are forthcoming. The results we've obtained to date, while still preliminary, suggest that Lilaeopsis is allied closely with four North American endemic taxa (Cynosciadium, Daucosma, Limnosciadium, and Ptilimnium) and, possibly, Oxypolis. Lilaeopsis occidentalis, native to the Pacific coast of North America, is sister to all other Lilaeopsis species, suggestive of a North American origin for the genus. Several species are likely not monophyletic, such as L. brasiliensis, L. polyantha and L. macloviana. Surprisingly, the ITS results suggest that L. schaffneriana var. recurva may not be a Lilaeopsis at all, but instead may ally with the genus Ptilimnium. Further genetic studies on this federally endangered taxon are underway, as is the procurement of cpDNA sequence data to confirm the ITS results.
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1 - University of Illinois Urbana, Department of Plant Biology, 239 Morrill Hall, 505 South Goodwin Avenue, Urbana, Illinois, 61801-3707, USA
2 - The State Botanical Garden of Georgia, 2450 S. Milledge Ave., Athens, Georgia, 30605, USA
nuclear ribosomal DNA.
Presentation Type: Oral Paper
Date: Wednesday, August 17th, 2005
Time: 8:15 AM