1896. ] Isoetes riparia and I. saccharata. 221 
ment, from 0.026 to 0.030™. The ‘‘tubercles” with which 
they are beset are more plentiful, and so more obvious than 
the papillae of the other species, but scarcely differ from them 
in appearance. 
I. saccharata. The structural variation here is apparently 
greater than in the other species, while any dioecious ten- 
dency is still to be detected. Plants were collected at the 
original station on Wicomico river, Sept. 14, 1895, where 
they grow plentifully in sand deeply overlaid with mud. 
These agree, for the most part, with the description of Engel- 
mann. But the leaves of mature plants are generally three 
to five inches long, and the macrospores 0.48 to 0.55” thick, 
with warts a good deal confluent, especially below, but not 
reticulated. The microspores measure 0.024 to 0,028™ long. 
The olive green color, the rather flaccid state of the leaves, 
and the constant narrow velum were sufficiently noticeable. 
The whole plant, though taller than one would expect, is of 
quite slight build. The trunk is very small. 
In 1895 I noted® the collection of this species in Elk river, 
at Piney creek cove and Back creek. In August of the same 
year it was observed in other places in the same river. As it 
“Pears there, it isa more robust plant than on the Wicomico. 
he leaves are somewhat stiffer, of a deeper green, and of a 
nearly uniform length of three to three and one-half inches. 
ough less flaccid, they are generally strongly curved, and 
their ends mostly rest upon the ground. The crown meas- 
wes One-half to three-fourths inch in diameter; the macro- 
‘Pores are 0. 40 to o. 48™" thick, with warts but little confluent 
above, blunt and not at all crested. The microspores are 
028 to 0.030" long, quite as long as those of /. riparia, but 
less Plentifully knobbed than the latter. The velum varies 
but little, never reaching more than one-fourth the sporan- 
gee The sporangium is sometimes 5"" long, while yuan 
f © Wicomico Plants is at most 3.5". The trunk is not ail- 
“rent from the typical trunk of the species. : hich 
f a August 12, 1895, two more forms of the species, whic 
ya study may show to be worthy of distinction as feat 
frst Were collected in Lloyd's creek, Sassafras river. 3 a 
a. these, the most robust form of the ie Fonds 
baria ¢ has almost precisely the general asp apn ate bove. It 
Collected at Pennsgrove, N. J., and described above. 
3 
Borantcar Gazette, 20: 32. Ja. 1895. 
