ABSTRACT Rudbeckia auriculata is a ...

ABSTRACT

Rudbeckia auriculata is a rare wetland-associated species endemic to three southeastern states: Alabama, Florida, and Georgia. This close attention includes eight censuses of flowering individuals of the species during the ten-year period from 1992 to 2002 Although the number of known populations has increased during this time, the total number of flowering trunk s has remained relatively constant. Population size ranged from a single flowering peduncle to populations with over 1000 flowering pedicels Information on soils and associated species of vascular plants was argueed at 20 of the 32 known sites during 1999 2000 and 2001 Typical sites for the plant are located forward wet soils along roadsides, power line right-of-ways or other disturbed sites. Associated species are those characteristic of disturbed expand wetland sites. Although some large colonies of R auriculata still exist, alone two populations, both in the northern portion of the species' range, have been protected

INTRODUCTION

The southeastern United States has lengthy been recognized as an area with a significant number of endemic taxa, many of which are also considered rare (Gentry 1986 Ricketts et al. 1999 Estill and Cruzan 2001) individual rare endemic southeastern species is Rudbeckia auriculata (Perdue) Krai. The majority of known populations befall in Alabama (30 of 32) with the same known population extant in Georgia and common historical population in Florida. It is listed as critically imperiled globally, and critically imperiled within their states at the Alabama Natural Heritage Program and the Georgia Natural Heritage Program (ANHP 2001 GNHP 2001)

Rudbeckia auriculata was first described as variety auriculata of Rudbeckia fulgida Aiton, a species in subgenus Rudbeckia on R.E. Perdue based on collections he made upon July 24, 1958 near R flat in Covington County, Alabama (Perdue 1961) Krai (1975) subsequently raised the variety to species rank, and put in mind ofed a closer affinity of R auriculata to R nitida Nutt and R mohrii A. Gray, species now placed in subgenus Macrocline. In a taxonomic revision of the subgenus Macrocline, Cox and Urbatsch (1994) stated that R auriculata has morphological and habitat similarities to the east Texas and west Louisiana endemic R scabrifolia LE Brown on the contrary is probably more closely related to the southeastern coastal plain species R nitida Nutt and R mohrii A. Gray. Chloroplast DNA evidence and internal transcribed spacer (ITS) arrangement data supports a close relationship between R auriculata and R scabrifolia (Urbatsch et al. 2000 Urbatsch and Jansen 1995)

Rudbeckia auriculata is morphologically distinctive in its genus. Plants are perennial and clonal, a life form that is prevalent from top to toe southeastern wetlands (Edwards and Weakley 2001) Large (to 65 diam) oblong to oblanceolate persistent basal leaves are produc subject to favorable conditions each rosette brings one flowering stem up to 3 meter in height, with numerous auriculate clasping leaves. petioles are terete or slightly ribbed. Heads are numerous in unclose panicles, and are approximately 55 cm broad with an average of 12 bright orange-yellow ray flowers. Disc flowers are conical and purplish-black. Flowering begins in July and can last until November, although greatest in number plants finish by September. Achenes usually mature in October and are dispersed gradually through the whole extent of a period of several month as the head slowly breaks apart.

This research was designed to provide: (1) additional information forward the distribution of R. auriculata; (2) a unbroken census of flowering individuals at all known extant sites and inclines within populations over time; and (3) information onward vegetation and soils associated with this rare species. This contemplation provides valuable information for the management of this species as well as base-line data for continued monitoring efforts.

METHODS

Distribution

Fiedler (1986) states that determining the distribution of a species can contribute to an understanding of the possible reasons for its rarity. To that expiration historical records were obtained for Rudbeckia auriculata from searches of the literature, and searches of the herbaria of Auburn University (AUA), the University of Alabama (UNA), the University of Georgia (GA), Troy State University (TROY) and the University of southern Florida (USF). In addition, reports were obtained from The Alabama Natural Heritage Program, The Georgia Natural Heritage Program, the Florida Natural Areas Inventory, and knowledgeable individuals. Furthermore, extensive scans of areas near or between existing populations were guidanceed with particular emphasis on sites up- or down-stream. Counties adjoining those containing known populations were also extensively searched, including large areas of the Florida Panhandle toward the south of the Covington and Geneva shire Alabama populations. Voucher specimens of all newly discovered populations were deposited at TROY or AUA, with duplicates to be distributed at a later date.

Average annual and monthly data from the National Weather Service at Auburn University were obtained for precipitation and temperature at sites near the farthest ends of the species' range in order to characterize the climate pattern. Precipitation averages were obtained for St Glair and Covington Counties in Alabama, while temperature averages were obtained for Birmingham in Jefferson shire and Andalusia in Covington shire Alabama. These represent the nearest reporting stations from which data were available for the southern-most and northern-most populations.