1Rbo6ora 



JOURNAL OF 



THE NEW ENGLAND BOTANICAL CLUB 



Vol. 8. February, 1906. No. 86. 



THE SALT-MARSH IVA OF NEW ENGLAND. 

 Harley Harris Bartlett. 



The northern and southern forms of the plant known as Iva fru- 

 tescens differ so widely in several ])oints that it seems best to treat 

 them as distinct species. The nortiiern plant, as it occurs in Massa- 

 chusetts, is a shrubby perennial from two to four feet tall, generally 

 found on the muddy banks of tidal streams and along salt-marsh 

 ditches. Each clump consists of from ten to a hundred or more stems 

 from a single woody base. The individual stems are simple below 

 the paniculate inflorescence except in a ery old plants, where branches 

 may occur several nodes below the inflorescence. Iva jrutesccns as 

 described by Small in the "Flora of the Southeastern United States" 

 is from 1 to 3.5 meters (.3-11.5 ft.) tall. No accessible specimens 

 show the base of this large southern form, but as nearly as can be 

 judged from herbarium material it has freely branched stems. This 

 is probably due to the fact that in the south the small branches are 

 not deciduous at the end of the growing season, but continue their 

 growth from year to year. 



The most noticeabU; difference between the two plants lies in the 

 leaves, which are much larger and broader In the northern plant than 

 in the southern. The stem leaves of all available specimens of both 

 species were measured and the results expressed as ratio of length 

 to breadth. The ratio varied from — L^ to „^- (average --V) in the 

 case of the northern plant, from j to ^ (average ^) in the ca.se of the 

 southern plant. That is, the leaves of the northern plant are relatively 

 twice as broad as those of the .southern. Other significant differences 

 lie in the heads and achenes. The head of the southern plant is about 

 4 mm. in diameter at maturity, whereas the head of the northern 



