116 MICHIGAN ACADEMY OF SCIENCE. 



A COXTRIBUTIOX TO THE KNOWLEDGE OF THE FLORA OF 



TUSCOLA COUNTY. 



BY CHARLES A. DAVIS, ALMA. 



(Read before the Academy April 1. 1898.) 



[Abstract.] 



On the .so called ^•Prairies'' of the bottom lands near the shore of Sag- 

 inaw Bar from the region of Bay Port southwestward, was found a group 

 of plants, a considerable number of whicli have not been previously noted 

 from the central or eastern parts of the state, and one plant was found 

 which was heretofore only known from the single station on the southern 

 border from which it ranges southwestward. The plants here found are 

 characteristically those of the prairies of Illinois and adjoining states, and 

 in Michigan they occupy a small area around the lower end of Lake Mich- 

 igan. The soil conditions are such as are frequently found along shores 

 of large bodies of water where deposition is taking place, i. e.. sandy 

 strips alternating with rich vegetable deposit or muck. It is probable 

 that local climatic conditions due especially to the presence of Saginaw 

 bay in the near vicinity are more directly responsible than favorable soil 

 conditions for the presence of this colony of southern and southwestern 

 plants in this place. If this is so, and is capable of proof, the region 

 should be a very profitable one for the introduction of special crops 

 which cannot be grown in less favorable localities so far north, as it is a 

 well known principle of agricultural economics that the farther from 

 the center of the greatest pi'oduction of a given crop, that crop can be 

 i-aised, the better price it will bring. No stations for the i)lants found, 

 intermediate between those in the southern part of the state and this 

 locality, are known. The most important plants found were Asclepias 

 purpurascens L.. A. Sullivantii Englm.. Acerates floridana (Lam.) A. S. 

 Hitch., Crataegus Crusgalli L.. Cacalia tuberosa Nutt., Ludwigia poly- 

 carpa Short & Peter. Lythrum alatum Pursh, Lacinaria spicata (L.). 

 Kuntze. nnd Silphium terebinthaceum Jacq. 



This paper was published in full in the Botanical Gazette, Vol. XXV. 

 No. 6, pp. -loS-S. and the discussion of tho entire flora of Tuscola county 

 will appear in a forthcoming bulletin of the State Geological Survey on 

 Natural Resources of Tuscola County. 



