22 ENGELMANN—THE GENUS ISOETES IN N. AMERICA. , [ 3^9 
4. I. echinospora, Durieu. One of the smaller species with 10 to 30 
or 40 soft bright green or sometimes reddish leaves, gradually and regu¬ 
larly tapering from a thick base to a very slender elongated point abso¬ 
lutely without stomata, 2 to 4 or sometimes. 5 inches long; sporangia 
orbicular to broadly oval, unspotted, with a narrow velum; macrospores 
0.40 to 0.50 mm. thick, densely covered with delicate, erect, truncate, or 
slightly forked spinules; microspores 0.030 to 0.034 mm. long, almost 
smooth.—Bull. Bot. Soc. Fr. 8, 164. . 
Onlyin Europe from Northern Italy to Germany, France and England* 
extending to Lapland and Iceland, but apparently not in America. 
In this country we have a series of forms which have been distinguished 
by eminent anthority, especially on account of the presence of stomata so 
various in number and often so difficult to discover, and of a slight differ¬ 
ence in the form and size of the microscopic spinules which cover the ma¬ 
crospores. I have thought best to unite them specifically with the Euro¬ 
pean type, though it seems strange that in the European plant stomata 
should be absolutely absent, and it must remain subject to individual judg¬ 
ment, if not doubt, which view ought to be preferred. Nearest to the Eu¬ 
ropean true I. echinospora stands the var. Braunii and the other extreme 
is var. muricata, wide-ranging forms of a single type. The same difficul¬ 
ties, the same doubts, and the same solution, we find in studying some 
foreign forms and especially those allied to I. velata of the south of Europe. 
* * Stomata few. 
I. echinospora, var. Braunii, Engelm. Rather small, with 13 to 15 
green or reddish-green erect or spreading, rather short (3 to 6 inches long) 
tapering, soft leaves, generally with few stomata towards the tip only^ 
sporangia orbicular to broadly elliptical, spotted, generally h or even | 
covered by a broad velum ; macrospores 0.40 to 0.50 mm. thick, rarely a 
little longer, covered with broad, retuse spinules, sometimes somewhat 
confluent, and then dentate or incised at tip; microspores 0.026 to 0.030 
mm. long, smooth.-Gray Man. 1. c. /. Braunii, Durieu 1 . c. 11, p. 101. 
s The most common species of our flora from New Jersey and Pennsylva¬ 
nia, northward and northwestward, sometimes on gravelly soil, at other 
places reported from soft mud, in ponds or slow-running streams, also 
near the banks of larger lakes or under the influence of tidewater, nor¬ 
mally submerged from a few inches to several feet, in dry seasons some¬ 
times getting out of water; associated with Eriocatdon septangulare , 
Lobelia Dorimana, Sparganium, Sctr^us, Eleocharis, etc. New Jersey: 
in tidewater of Tom’s river, a slender long-leaved form, C. F. Parker 
C. E. Smith, and others; in a'lake in Morris Co., T. C. Porter. Pennsyl¬ 
vania: Montrose, Susquehanna Co., A. P. Garber ; Great Lake, Pocono 
Mountain, Porter & Canby ; Presque Isle, Erie, A. P. Garber. New York : 
Catskill Mountains in the lake near the hotel, G. TV. Clinton; Round Lake 
above Bolton, west of Lake George, on white sand, and in Lake Placide 
L. Lesquereux; Luzerne Lake and in Niagara river below Buffalo, G. W. 
Botanical 
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