|Comanche-peak Prairie-clover, Reverchon dalea|
|Kim Taylor (updated 5/31/2017)|
|Available for Sponsorship|
The following Participating Institutions are custodians for this species in the CPC National Collection:
The Lady Bird Johnson Wildflower Center
Botanical Research Institute of Texas
The conservation of Dalea reverchonii is not currently sponsored.
Kim Taylor (updated 5/31/2017) contributed to this Plant Profile.
Comanche Peak prairie-clover is a low, spreading perennial, which appears as a dense, mat-forming rosette up to 16 inches in diameter. Numerous thick, 3 inch long spikes of rose-pink to magenta-purple flowers bloom in May, before other Dalea species, and continue through June. The smooth, alternate, pinnate leaves are about an inch long.
Until recently, this elusive prairie-clover had been found only in a narrow band through three counties in north-central Texas. Julien Reverchon first collected this member of the pea family in 1882 from "the rocky top of Comanche Peak". Repeated surveys failed to re-locate that particular population (TPWD, 2003), until Spring of 2003 when a few plants were again found on Comanche Peak (Carr, personal commmunication.).
Distribution & Occurrence
Shallow calcareous clay to sandy clay soils over limestone in grasslands or openings in post oak woodlands, often among sparse vegetation in barren exposed sites. Most known sites are underlain by WalnutLimestone, a Cretaceous formation. Associates include Aristida spp., Bouteloua rigidiseta, Arenaria stricta, Dalea aurea, D. enneandra, D. tenuis, Evolvulus nuttallianus, Hedeoma drummondii, Hedyotis nigricans, Heliotropium tenellum, Indigofera miniata var. leptosepala, Paronychia virginica, Pediomelum reverchonii, Salvia texana and Thelesperma filifolium. (TPWD 2003; Taylor & O'Kennon 2013)
Dalea reverchonii is a calciphile, known to grow only on rocky limestone substrate Cretaceous in age. Mahler (1984) described the habitat as thin soil overlying limestone rock. Orzell (1987) noted that plants were found growing on a nearly flat Goodland Limestone (Cretaceous Age) Glade surrounded by shrub thickets (Orzell 5581, TEX). OKennon (2010) and Swadek and Burgess (2012) disagreed on the type of geology, noting that the species is restricted to Walnut Limestone glades. Much of the Walnut (Kwa) and Goodland (Kgl) limestones are mapped as undivided units (i.e. Kgw), possibly leading to the uncertainty in geology. Comanche Peak, the type locality for the species, is topped with Edwards Limestone (Ked). Dalea reverchonii has only been collected in limestone substrate on what have been termed limestone glades by Swadek and Burgess (2012). These glades consist of little to no soil overtopping limestone bedrock. Dalea reverchonii appears restricted to crevices in exposed limestone bedrock, very shallow soils over bedrock, or Walnut marl where the shell hash has been removed. The roots are embedded in the Walnut marl directly below the indurate Texigryphaea mucronata shell hash. The plant was rarely seen where vegetative cover is taller and denser, which seems to be associated with deeper soils overlying the limestone.
|The Nature Conservancy conducted a survey during the Spring of 2003 and now reports 35 known populations in the Hood/Parker/Wise Counties area, including the re-location of the original population (now ~6 plants) on Comanche Peak (Carr, personal communication.).
Taylor and O'Kennon (2013) conducted a survey in 2012 where they identified 33 new populations in five additional counties, bringing the total population number to 69 sites. Population numbers range from a single plant to over 1000 plants.
Conservation, Ecology & Research
Place some populations under protection
More managing agency awareness at field level
Texas Parks & Wildlife Department. 2003. Guide to the Rare Plants of Texas. Unpublished manuscript.