The Fort Worth Prairie

The Fort Worth Prairie (also known as the Grand Prairie) is a vast grassland with gently sloping, almost level plains dissected by valleys along rivers and streams. This prairie ecosystem is underlain by limestone geology with limestone bedrock near the surface across most of the region. This limestone gives the Fort Worth Prairie its unique features. Thin soil overtop of limestone restricts root penetration limiting the growth of woody vegetation. The area historically supported a vast grassland with woody vegetation mostly limited to river edges, hilltops, or mesas where soil was deeper and moisture more plentiful.

BRIT botanists have been studying the plants and ecology of the Fort Worth Prairie for several years. The primary goals are:

1.     Document the flora of the Fort Worth Prairie;

2.     Understand the distributions of rare and endemic species that grow in the Fort Worth Prairie;

3.     Understand the environmental factors that influence where plants grow on the Fort Worth Prairie; and

4.     Understand the plant community types of the Fort Worth Prairie.

This project consists of several smaller projects, each with a narrowly defined scope. When combined, these projects will give us a greater insight into the plants of the Fort Worth Prairie.

Distribution of Dalea reverchonii, Gratiola quartermaniae, and Isoetes butleri

In the spring of 2012, BRIT botanists conducted extensive surveys of limestone prairies, barrens, and glades in the Fort Worth Prairie and northern Limestone Cut Plain of north central Texas. Areas where limestone outcrops form “glades” reminiscent of the cedar glades found in the Central Basin of Tennessee were searched for Gratiola quartermaniae, Isoetes butleri, and Dalea reverchonii. Satellite imagery and geologic maps were used to identify other possible locations for exploration. When a plant was found, herbarium collections were made. Specimens can be viewed on BRIT’s online digital herbarium.

Dalea reverchonii (Comanche Peak Prairie Clover):

Dalea reverchonii was discovered in 1882 by botanist Julien Reverchon at Comanche Peak in Hood County, Texas and was described as a new species in 1886. The species was collected again in 1900 but was not seen for 64 years afterwards, until 1964 when Barneby collected the species near Springtown, Texas. Several botanists have worked to find the species through the years. The species only occurs on Walnut Limestone outcrops of the Fort Worth Prairie.

During the 2012 survey, BRIT botanists documented 33 new populations of Dalea reverchonii, bringing the total to 69 sites. All of the populations occur in 8 counties in north central Texas. The species is highly restricted in its habitat preference and is one of the most unique plant species in north central Texas.

In October, 2014 Kim Taylor and Bob O’Kennon partnered with Texas Parks and Wildlife to train Texas Department of Transportation workers about the habitat of Dalea reverchonii. Taylor and O’Kennon lead a field trip to 8 sites in the area to show TXDOT employees what the plant looks like, how to identify it, and what the habitat looks like. This work will help prevent future losses of this rare species due to road construction.

CITATION: Taylor, K.N. and R. J. O’Kennon. 2013. Ecology and distribution of the north central Texas endemic Dalea reverchonii (Fabaceae). J. Bot. Res. Inst. Texas 7:603–610.

 

 

Gratiola quartermaniae (Quarterman’s Hedge Hyssop):

Gratiola quartermaniae was first described from Eastern North America by Estes and Small in 2007. The species typically grows in thin, seasonally saturated soil over exposed limestone or dolomite bedrock. This habitat is typically found associated with limestone glades, barrens, prairies, and alvars. A limestone glade is an area of exposed limestone bedrock with little to no soil overtop. The species is most common in the limestone cedar glades of central Tennessee and northern Alabama, though it also occurs in primarily limestone habitats in northeastern Illinois, central Texas, and southeastern Ontario. Similar distribution patterns are seen in several other species which grow with G. quartermaniae including Clinopodium arkansanum (Nutt.) House, Grindelia lanceolata Nutt, Heliotropium tenellum (Nutt.) Torr., Isoetes butleri Engelm., Juncus filipendulus Buckl., and Minuartia patula (Michx.) Mattf.

During the 2012 search, 49 new locations were identified for G. quartermaniae. These collections represent 7 new county records, including Bosque, Denton, Hood, Johnson, Parker, Tarrant, and Wise counties.  At least one voucher specimen from each county was collected and deposited in the BRIT herbarium. All populations were found on seasonally wet Walnut Limestone glades and are the first to be found in the Texas Fort Worth Prairie and Limestone Cut Plain. These collections indicate that the species and its calcareous glade habitat are much more abundant in Texas than previously thought.

CITATION: Taylor, K.N. & R.J. O’Kennon. 2014. Expanded distribution of Gratiola quartermaniae (Plantaginaceae) in Texas, U.S.A. J. Bot. Res. Inst. Texas 8(1):333–337.

Isoetes butleri (Limestone Quilwort):

Isoetes butleri is a species of fern that grows in limestone outcrops across most of the Eastern United States. The species was known to occur in a few sites in Texas but was unknown in north central Texas. BRIT botanists discovered the species in the limestone prairies of north central Texas, where it appears to be very common, with 125 populations. The species is a common member of limestone glade seep communities. It can be seen in shallow soil overtop of limestone bedrock in areas where seasonal seepage keeps the ground wet during the spring.

CITATION: Taylor, K.N., R.J. O’Kennon, and T.F. Rehman. 2012. Expanded distribution of Isoëtes butleri (Isoëtaceae) in Texas. J. Bot. Res. Inst. Texas 6:753–757.