Ludwigia macrocarpa. 51 



The genus Ludwigia was named by Linnseus in honour of Chris- 

 tian Theophilus Ludwig, Professsr of Medicine in the University of 

 Leipsic, and author of many celebrated works on Botany and Medi- 

 cine. It is a numerous genus. In North America there are thirteen 

 species, most of which are indigenous to the southern states. The 

 specific appellation, macrocarpa, was given by Michaux to designate 

 its large capsule: but as some other species possess this character, 

 it is scarcely a better name than alternifolia, which it was intended 

 to amend, because of its expressing a character not constant in the 

 plant, the leaves being frequently opposite As the latter specific 

 term actually led to misconception or error, the less exceptionable 

 one by which the plant is here noticed, has been preferred. This 

 is the commonest species of Ludwigia in Pennsylvania, where it is 

 decidedly perennial. It appears strange that so many writers have 

 regarded it as annual. Mr. Elliot, however, has found it perennial 

 in Georgia. The L. pilosa which it much resembles, its hairyness 

 apart, is often found with it, inhabiting similar situatious. L. macro- 

 carpa is very common in the vicinity of this city, and the pilosa very 

 rare. 



Fig. 1. A flowering specimen. 



2. A petal. 



3. The germ, stamens, and pistil. 



(All the size of nature.) 



