BicKNELL : Ferns and flowering plants of Nantucket 3 



Xyris caroliniana Walt. 



Local, but common about some of the bogs in Polpis ; Almanac 

 Pond ; bog west of Sankaty. 



ERIOCAULACEAE 



Eriocaulon septangulare With. 



In shallow water or wet sand about the borders of a number 

 of ponds, especially Tom Never*s, Gibbs* and Maxcy^s ponds, and 

 smaller ponds in Polpis. Leaves beginning to show June 8 ; some 

 fresh heads after the middle of September. 



COMMELINACEAE 



* Tradescantia virginica L, 



sparingly established on roadside banks at several places near 

 the town in dry sterile soil. First noticed Aug. 6, 1906 — leaves 

 only; first flowers June 8, 1908. 



PONTEDERIACEAE 



Pontederia cordata L. 



Very common in ponds and pools. Leaves just appearing 

 June 8 ; still some flowers late in September. In the autumn the 

 leaves often become deep blackish-purple. 



* Pontederia cordata angustifolia (Pursh) Torn 



The narrow-leaved pickerel weed may be merely a state or 

 condition of the common species, but until this has been estab- 

 lished by proof it seems proper to allow it separate recognition. 

 On Nantucket it contrasts strikingly with typical cordata and 

 seems to maintain its leaf characters under diverse conditions. 

 The leaves, although often very narrowly triangular-lanceolate, 

 may be equally broad with those of cordata^ but they are more 

 tapering and are truncate to openly cordate at the base instead of 

 ueeply sagittate-cordate as are the ovate to ovate-oblong leaves 



of the typical plant. 



It is common in several of the Polpis ponds and I did not find 

 it anywhere mixing with the cordate-leaved species. 



Heteranthera dubia (Jacq.) MacM. 



Reported by Mrs. Owen from Long and Miacomet ponds on 

 the authority of Mr. Morong ; I did not meet with it. 



