﻿554 Bicknell: Ferns and flowering plants of Nantucket 



east of the middle of the island it almost entirely replaces N. serpen- 

 tarius of the western side, the two species rarely being found near 

 together. In full flower August 30, 1904; continues in bloom 

 through September. 



On the exposed plains this species becomes even more dwarfed 

 than the preceding, sometimes not exceeding 1.5 dm. in height 

 when fully mature. This open ground form displays much 

 purplish coloration which deepens to blackish purple in the upper 

 parts and the involucres in marked contrast with the clear white 

 rays. Its leaves are firm and unusually small, with their narrow 

 deeply parted divisions and lobes cuspidate-acute; the bracts of 

 the involucre are usually narrowly attenuate. A markedly con- 

 trasting form found in shaded thickets is taller and slenderly 

 branched, little if at all purpHsh tinged, and with more ample and 

 thinner leaves, except the lowermost often nearly entire or merely 

 hastate lobed ; the involucral bracts are commonly shorter and less 

 tapering than in the contrasted form and the rays yellowish 

 instead of clear white. 



AMBROSIACEAE 



* IvA ovaria Bartlett. 



Iva frutescens auct. non L. 



This characteristic salt marsh plant, here close to the northern 

 limit of its range, I have seen nowhere else on Nantucket than near 

 the harbor shore about Acquidness and Abram's Points where it 

 thrives by the tide pools and along the marshes. Just in flower 

 September 3, 1904. 



* IVA XANTHIIFOLIA Nutt. 



A single large plant in flower and fruit near the wharves 

 September 15, 1904. A vigorous group on Howard Street, July 

 12, 1 91 2, the tallest plants four feet high and the inflorescence 

 just beginning to appear. This same colony had been observed by 

 Mrs. Flynn August 17, 191 1, and was also discovered by Miss 

 Grace Brown Gardner, who has sent me fruiting specimens 

 collected September i, 1913. 



The plants from these two stations seem to represent two 

 rather distinct forms of the species, one having leaves triangular- 



