VEGETATION OF LITTORAL BELT. 129 



occupy almost alone the alluvial banks bordering the swamps, covered 

 with the debris left behind after every overflow. 



LITTORAL BELT. 



This division of the coast plain comprises the outlying islands and 

 the narrow strip under the influence of the salty tide. Either sandy 

 or marshy, this Littoral belt presents three distinct formations in its 

 flora: (1) The plant formation of the strand or sandy flat beach, with 

 its shingle and salty pools; (2) the plant formation of arid drifting 

 sands, (3) and lastly the salt marsh. 



Halophytic plant associations of the strand. The strand or sandy flat 

 beach, of moderate extent, as found in Baldwin County, washed by 

 the more or less brackish water of Mobile Bay and the smaller inlets 

 to the east of this sheet of water, is almost destitute of vegetation. 

 The flora of the strand lining the Gulf shore, always moistened by 

 the salt spray of the surf and flooded by high tides, is poor in individ- 

 uals and species. The species found are, many of them, at home on 

 tropical shores, and they constitute a very open association of sand- 

 loving, salt-water plants (halophytes), similar to fazlpomaeapes-capreae 

 formation of tropical strands. This fine halophyte of the morning- 

 glory family, from which this association has received its name, is not 

 rare on our Gulf shore. Its interlaced stems form large patches, 

 which at once attract the attention by the rich dark green of their 

 fleshy broad leaves and by their large rose-purple flowers. Sesumum 

 portulacastrum inhabits the shallow salty pools with Cakile maritima 

 geniculata, both frequent in the West Indies; also withJva imbricata, 

 a low shrubby perennial of southeastern North America, and Dondia 

 (Siwda] linearis, common on the Atlantic and Gulf shores from New 

 England to Florida and Mississippi. 



Xerophile plant associations of the dry sands of Mobile and Perdido 

 l)ays. The benches of loose white sand extending along the shore of 

 Mobile Bay and the land-locked waters of Perdido Bay present a varied 

 vegetation of sand-loving plants (psammophytes), which are so scat- 

 tering, however, as scarcely to hide the snow-white sands. When 

 viewed under the glare of the noonday sun, the dark-green foliage of 

 the stunted live oak, with gnarled limbs, stands out in strong contrast 

 with the glistening sands. The stiff, leathery, narrow leaves, shining 

 above and hoary beneath, peculiar to this maritime form, afford a safe 

 protection against the injurious effects of excessive transpiration dur- 

 ing a long-continued drought, when the sand is heated by the scorching 

 rays of the summer sun. 



The grasses are: 



Panicum repens. Cenchrus incertus (sand bur) . 



Panicum littorale. Cenchrus megacephalus (sand bur) . 



Stenotaphrum secundatum (Saint Augus- Sieglingia purpurea (purple sand grass) . 



tine grass) . Sieglingia americana (Southern sand grass. ) 



15894 9 



