94 Mr. Geyefs Plants of Illinois and Missouri. 



Art. XIII. — Catalogue of a collection of Plants made in Illinois 

 and Missouri, by Charles A. Geyer; with critical remarks, fyc. 

 by George Engelmann, M. D., of St. Louis. 



Mr. Geyer, who is an excellent collector, is now absent on an 

 expedition to the Rocky Mountains and Oregon, as announced in 

 the last volume of this Journal, (p. 226.) Being unwilling to 

 adopt the common plan of selling his collections to subscribers 

 before they are actually made, he prefers to seek some needful 

 aid in the prosecution of his arduous undertaking, by offering to 

 the botanical public sets of the following plants, collected in 1842 

 near St. Louis, Missouri, and around Beardstown on the Illinois 

 River. This collection (which is duly mentioned on p. 227 of 

 Vol. xlv,) consists of the following species. 



1. Ranunculus micranthus, Nutt. Apparently common in the 

 grassy river bottoms, and on fertile grassy hills in Missouri and 

 Illinois. It is very near R. abortivus, but apparently well distin- 

 guished by its pubescence, and the more orbicular, very seldom 

 cordate or reniform lowest leaves. 



2. Ranunculus fascicularis, Muhl. 



3. Myosurus minimus, Linn. Certainly a native plant.* 



* Wc now ought to be careful observers of such plants as arc apparently com- 

 mon to both continents: in after years it will be much more difficult to decide 

 which are natives and which introduced. Many European plants, now common 

 weeds east of the Alleghany Mountains, have not yet found their way to the Mis- 

 sissippi valley, but undoubtedly will arrive in a short time. Other plants are here 

 already as common as they are in Europe, from whence they were derived, or in 

 middle Asia, perhaps their original home. It behooves us therefore to note the 

 progress of these intruders, and distinguish from them the true natives. 



We are able to distinguish several different classes of such plants: 



1. Nearly allied geographical species, where one takes the place of the other in 

 the other continent; such as Quercus alba in North America, and Q. pcdunculata 

 in Europe; Carpinus Americana and C. Betulus ; Polygonum Persoonii (n. sp. P. 

 mite, Pers.) and P. mite, Schrank; Androsace occidentalis and A. elongata; Lyco- 

 pus sinuatus and L. Europmus, and many others. 



2. Geographical varieties, where no specific distinction can be discovered be- 

 tween the natives of both continents, but where the American and European va- 

 riety can always be distinguished by some points of minor importance. Such are 

 Slum laiifolium, Circcca lutetiana, Samolus Valerandi, (if it does not belong to the 

 first class,) Castanea vesca, Lcpidium ruder ale, Astragalus hypoglottis, Eriophorum 

 gracile, Myosurus minimus, etc. 



3. Identical plants, true natives of both continents, especially arctic or at least 

 northern plants ; also marine species and cryptogamic plants ; e. g. Potentilla an- 



