2 UNIVERSITY OF MISSOURI STUDIES ['44 



mores form a noticeable fringe. In places alluvial flats are cov- 

 ered with elms, soft maples, basswoods and other bottoms' trees. 

 In all these the oaks occupy a subordinate position, though they 

 are by no means uncommon. There are also treeless marsh 

 meadows, and ragweed flats, where a paludose and subaquatic 

 flora exists, and in the ponds, lakes and streams there is a 

 strictly aquatic vegetation. 



In the other direction on the hills and cliflfs, while the oaks 

 are still in a measure dominant, the herbs and shrubs are quite 

 different from those of the forest plain. The vegetation fre- 

 quently assumes xerophytic forms, while on the rocks and ledges 

 rupestrine plants form a very distinct society. 



The forest plain is now poorly preserved. Its adaptability 

 to agriculture has caused most of it to be cleared into fields and 

 pastures. Between the cultivated field and the virgin forest — 

 and none of the present forests are strictly virgin — lie all stages 

 of primitiveness. There are pastured forests where the flora of 

 the forest floor is ruined; there are underbrushed tracts, either 

 lapsing back into forest, or becoming half-wild pastures. 

 There are large park-like areas, where numerous trees, especially 

 species of Juglans and Carya, are left, and where patches of 

 Symphoricarpos vulgaris and Ribes Missouriense are forming 

 the nuclei of thickets, or where species of Vernonia, Rudbeckia 

 and Teucrium give the appearance of a prairie. There are also 

 hawthorn glades of considerable extent, especially in the 

 northern portion of the region. 



3. FLORISTIC POSITION OF THE FLORA. 



Before entering into details in regard to the ecology of 

 the region, it is profitable to consider the floristic position of 

 the flora. Disregarding weeds and other introduced plants the 

 vegetation has a fivefold origin. Columbia lies on the boundary 



