taries dissect this region. In eastern and southeastern Texas are to be found 

 evergreen shrub bogs and savannahs. In this same area as well as in Oklahoma 

 are to be found swamps, alluvial woodlands and floodplains, and along coastal 

 Texas are to be found vast fresh and brackish marshlands, rice paddies, ocean 

 beaches and shores, drainage canals, bays, reefs, estuaries and sluggish streams. 

 Inland, especially in areas of low rainfall throughout our region, are to be found 

 irrigation ditches, lakes on salt deposits, and saline and alkaline flats that are 

 periodically inundated. In these more arid regions are to be found rivers and 

 streams that may have their beginnings in springs and artesian wells at high 

 mountain elevations but which disappear as dry beds as they flow into the 

 lowlands. 



When a body of water is created by man, usually the first obvious plant 

 invaders are cat-tails (Typha); their essentially weightless wind-blown seeds 

 would appear to be hovering nearby. Next, or occasionally invading simultaneous 

 with cat-tails, are bulrushes (Scirpus). These early invaders first establish them- 

 selves in shallow water and then, through clonal growth by means of rhizomes and 

 stolons, migrate out into deeper water where they form dense conspicuous colonies 

 that provide a habitat for small floating plants and they give protection and 

 shelter to various wildlife. 



As noted above, similarly to natural lakes in the North, these southwestern 

 artificial lakes and ponds, when stabilized, also typically have several zones of 

 vegetation. The outermost zone is one of emergent vegetation, wherein the plants 

 are rooted in the lake substrate and the photosynthetic organs stand above the 

 surface of the water. Here we find primarily grasses, rushes and sedges, among 

 which are spike rush (Eleocharis), sedge (Carex), bulrush (Scirpus), bur-reed 

 (Sparganium), cat-tail (Typha), water plantain (Alisma) and arrowhead 

 (Sagittaria). 



The next zone, moving lakeward, is that of floating-leaf plants. These plants 

 may be rooted in the lake substrate or they may be free-floating. In either case, 

 they have their leaves floating on the surface of the water, or, in some instances, 

 with some leaves raised above the surface of the water. Among these plants are 

 water shield (Brasenia) , yellow water lily (Nuphar), white water lily (Nymphaea) , 

 pondweed (Potamogeton) , water ferns (Azolla and Ceratopteris), water hyacinth 

 (Eichhornia crassipes), water lettuce (Pistia Stratiotes) , duckweed (Lemna), 

 duckmeat (Spirodela) and water meal (WoJffia). 



The innermost zone is composed of entirely submersed plants or those with 

 only their flowering and fruiting parts emersed or floating. These plants are 

 characterized by having long, sinuous or straplike leaves and with a bunched 

 growth habit and finely dissected highly branched leaves. These plants derive gases 

 and nutrients from the water in order to survive. Among these plants are milfoil 

 (Myriophyllum), hornwort (Ceratophyllum) , naid (Najas), waterweed (Egeria, 

 Elodea) and fanwort (Cabomba caroliniana) . The non-vascular plants, stonewort 

 (Chara and Nitella), are also frequently abundant in this zone. 



This phenomenon in nature that can be "a thing of beauty," the zonation of 

 life forms of undisturbed, natural aquatic vegetation that becomes established 

 and is so prevalent about the shores of lakes, ponds, canals and slow-moving 

 streams, when once destroyed or disturbed by man's "improvements," or his 

 propensity for gross pollution, is essentially impossible to re-establish. Since this 

 zonation is the result of natural succession by plants in this type of habitat, they 

 should be left undisturbed if man is to maintain his aquatic environment as it 

 should be in such places. 



Coastal marshes, known to support numerous species of plant and animal life, 

 are among the most important of all natural habitats. In these areas a very slight 

 change in elevation will also mean somewhat of a change in the vegetative cover. 



