Broomsedge bluestem is dominant in a 15-mile-long area surrounding the PAIS ranger 

 station, while seacoast bluestem forms an extensive midheight grassland to the south 

 (especially in the Big Shell area) and on the extreme northern end of the island. On southern 

 Padre, which has suffered more extensive hurricane surge damage, the grassland is 

 discontinuous, and entirely absent in some large stretches. However, the composition is 

 similar to the north end, except broomsedge bluestem and the Dicanthelium panicums are 

 absent. Bordering the mudflats on the Laguna Madre shores, on both north and south Padre 

 Island, shoregrass (Monanthochloe littoralis) is dominant. 



The spring flora is characterized by many showy forbs. Beach evening primrose 

 (Oenothera Drummondii), wliitestem wild indigo (Baptisia leucophaea), and gentians 

 (Eustoma exaltatum, and Sabatia arenicola) are among the conspicuous and widespread 

 species. In fall, wooly croton (Croton capitatus), gulf croton (Croton punctatus), prairie 

 senna (Cassia fasciculata), scarlet pea (Indigo j 'era miniata) beach groundcherry (Physalis 

 viscosa), western ragweed (Ambrosia psilostachya), and camphorweed (Heterotheca 

 subaxillaris) comprise many of the dominant forbs. 



Most mid-island hummock dunes and ridges have remnants of sea oats in addition to the 

 above-listed species. Swales and shallow depressions vary in size from small potholes to 

 extensive marshes with typical aquatic vegetation. Although there are few permanent 

 freshwater marshes, in wet years extensive ponds may be present year around. Shallow 

 depressions are often covered with saltmeadow cordgrass, but those with longer-standing 

 water often have tule (Typha domingensis), rattlepod (Sesbania Drummondii), and the tall 

 sedges Eleocharis interstincta and Scirpus americanus, plus other species of small sedges 

 (Eleocharis spp. and Cyperus spp.). Seashore dropseed usually covers the exposed ground 

 surface when the depressions are dry. Lagunal saline mudflats, subject to periodic 

 inundation, develop a cover of glasswort (Salicornia perennis, and S. Bigelovii), and sea blite 

 (Suaeda spp.). On slightly more elevated areas, shoregrass, sea oxeye (Borrichia frutescens), 

 and camphor daisy (Machaeranthera phyllocephala) are found. 



The number of species on the shoreface of the dunes is limited, with sea oats the 

 dominant sand-trapping plant (Fig. 6). Other species capable of trapping or binding sand are 

 saltmeadow cordgrass, seashore dropseed, bitter panicum, railroad vine (Ipomoea 

 Pes-caprae), and gulf croton. After dunes have been started by pioneer vegetation, forbs 

 such as beach groundcherry, beach evening primrose, and prairie senna often become 

 common. 



To supplement a visual description of the island vegetation, and to help document 

 changes after Livestock removal, quantitative vegetation measures were made in August 

 1971, and repeated in August 1973. Transects were established in four zones: (a) backshore, 

 about 100 feet shoreward of the foredunes; (b) foredune foreslope (windward slope): 



(c) middune area, leeward of the primary dune crest, but in the foredune complex: and 



(d) mid-island prairie, mostly flat grassland, with occasional scattered dunes and depressions. 



35 



