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44 : BOTANICAL GAZETTE [JANUARY 
idea of the zonation may be gained. In such places the second 
zone contains some Ambrosia, but the dominant species are various 
grasses and sedges, especially Leersia oryzoides and Glyceria nervata. 
Bidens aristosa is common, and there are numerous scattered plants 
of the species mentioned before. Within and below this zone isa 
third, in which the-dominant plants are again grasses and sedges, 
and in which Iris versicolor, Mimulus ringens, Penthorum sedoides, 
Lippia lanceolata, Asclepias incarnata, Lobelia siphilitica, and other 
Fic. 2.—Relation of vegetation to topography; the drained slough in the fore- 
ground, with prominent clusters of Iris, is contrasted with the forest-covered ridge 
at the leit——Photograph by ArtHur G. VESTAL. 
characteristic hydrophytes are abundant. A fourth zone at the 
margin of the pond is characterized by Scirpus validus, Salix 
longifolia, Eragrostis hypnoides, Eleocharis obtusa, E. acicularis, 
and Ludvigia palustris. 
It has not been many years since all the sloughs contained 
permanent standing water, which has been removed by tile drains 
or open ditches. By this the fourth, or innermost, zone has been 
destroyed completely, the third has been limited to a few scattered 
relics, and the second has extended in and occupied most or all 
of the space. Then pasturage has destroyed the dominant grasses 
and sedges and caused the invasion of weedy species. 
