Common (Translated Scientific) Name: Widow''s-cross - Drummond''s Onion - Sunbright - Lady Bird''s Centaury / Common Nostoc Forbland

Colloquial Name: Blackland Prairie Limestone Glade Ephemeral Pool

Hierarchy Level:  Association

Type Concept: This association accommodates seasonally wet limestone glades of the blackland prairie region of Texas. These glades are typically on the upper rims of gradual to moderately steep slopes, in areas exceeding 1 ha, and inter-dispersed among tallgrass prairie dominated by Schizachyrium scoparium, Sorghastrum nutans, and Carex microdonta. The lower slopes of the prairie typically grades into a woodland dominated by Quercus muehlenbergii, Quercus velutina, Ulmus rubra, Juniperus virginiana, Juniperus ashei, Fraxinus americana, Cercis canadensis, Rhamnus lanceolata, Cornus drummondii, Rhus aromatica, and Styphnolobium affine. Ground and limestone pool moisture during late winter is prevalent. This glade vegetation has developed on the Gober Chalk, Pawpaw, and Lavender Outcrop formations and characteristically occupies depressions in the limestone which hold water in the winter and early spring. These areas become desiccated and baked in the heat of summer. Characteristic plants are the annuals Sedum pulchellum and Centaurium texense, and the perennials Allium drummondii and Phemeranthus parviflorus. The blue-green alga Nostoc commune forms mats. Other wet pool specialists include Crassula drummondii, Rotala ramosior, and Valerianella amarella. Characteristic taxa that occupy the pools when they dry out include Sporobolus vaginiflorus var. ozarkanus, Sporobolus vaginiflorus var. vaginiflorus, Minuartia patula, Houstonia micrantha, Portulaca sp., Galium virgatum, Croton monanthogynus, and Chamaesyce nutans. Other taxa that are commonly found in crevices of limestone sheets and drier edges include Bouteloua curtipendula, Bouteloua rigidiseta, Paronychia virginica, Lesquerella gracilis, Tetraneuris linearifolia, Asclepias asperula, Heliotropium tenellum, Stenaria nigricans, Hedeoma reverchonii, Draba cuneifolia, Anemone berlandieri, Opuntia sp., Lithospermum incisum, Thelesperma filifolium, Zigadenus nuttallii, Orobanche sp., Penstemon cobaea, Spiranthes magnicamporum, and Evax verna.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: These glades were surveyed in 1999 by the concept author and Dr. Walter Holmes (Baylor University Plant Taxonomist). Most of the survey work was conducted in spring and early summer, and more examination of the fall flora is needed.

Similar NVC Types: No Data Available

note: No Data Available