368 BICKNELL: FERNS AND 
Swain’s Neck, only just in flower September 17, 1907, were of a 
different form. 
Zanichellia palustris L. Fresh water ditches in Shawaukemmo 
Spring meadow; abundant in a salt creek on Little Neck, where it 
was flowering and fruiting freely June 22, 1910. At both stations 
‘the plants appeared to be perfectly typical of var. pedunculata 
J. Gay, the peduncles becoming 1-3 mm. long and bearing stipitate 
nutlets; these were denticulate, and margined along the dorsal 
ridge by a narrow semi-transparent membranous expansion. 
Naias flexilis (Willd.) Rostk. & Schmidt. A second station is 
Hummock Pond where it was collected by Miss Gardner, Septem- 
ber 12, 1915. 
Natas guadalupensis (Spreng.) Morong. In Hummock Pond, 
the third Nantucket pond in which it is now known to occur. 
Triglochin maritima L.- In flower as early as May 30, 19090; 
some plants still in bloom July 10, 1912. 
Alisma subcordatum Raf. Pool north of the town, 1908; 
pool not far from the original station, 1912. 
Sagittaria Engelmanniana J.G.Sm. In early flower July 10, 
I9I2. 
Sagittaria latifolia Willd. <A large form occurs at No-Bottom 
Pond having the leaf blades and their basal lobes narrowly elon- 
gated and tapering, sometimes becoming over 20 cm. in length 
while only 10 mm, wide at the base. 
Panicum linearifolium Scribn. True P. linearifolium has not 
been collected on Nantucket. The grass somewhat intermediate 
between it and P. depauperatum, previously referred, with reserva- 
tions, to P. linearifolium, has been determined by Professor 
Hitchcock to be the variety of P. depauperatum mentioned by 
Hitchcock and Chase in North American species of Panicum 
(Contr. U.S. Nat. Herb. 15. 1910), p. 152. 
Panicum Owenae Bicknell. A fully developed mature tuft, 
_ collected July 1, 1912, well attests the distinctness of this grass 
from P. Addisonit Nash, to which less perfect examples were 
referred by Hitchcock and Chase (North American species of 
