—7_ 
aa 
THE GENUS ISOETES IN NORTH AMERICA. 463 
then dentate or incised at tip; microspores 0.026 to 0.030 mm. long, smooth. —Gray, Man. lc. I. Braunii, Durieu, 
Ol. 
he most common species of our flora from New Jersey and Pennsylvania northward and northwestward, some- 
times on gravelly soil, at other places reported from soft mud, . (aed or slow-running streams, also near the banks 
of larger lakes or under the influence of tidewater, normally submerged from a few inches to several feet, in dry 
seasons sometimes getting out of water; associated with rccdnten septangulare, Lobelia Dortmanna, Sparganium, 
Scirpus, Hleocharts, ete. New Jersey: in tidewater of Tom’s River, a slender long-leaved form, C. F. Parker, C. E. 
Smith, and gical ; in a lake in Morris Co,, T. C. Porter. Pennsylvania: Montrose, Susquehanna Co., A. P. Corker : 
Great Lake, Pocono Mountain, Porter & Canby; Presque Isle, Erie, A. P. Garber. New York: — Mountains 
in the lake near ae hotel, G. W. Clinton ; ant Lake above Bolton, west of take George, on Ww 
sand, and in Lake Placide, LZ. Lesquereux ; Luzerne Lake and in ein River below Buffalo, ah W. on (23) ] 
Clinton ; at the head of Goat Island, Niagara, between stones, G. Engelmann; Oneida Lake, J. A. P. 
in Oswego River, F. Pursh, probably (see p. 358). Massachusetts : ie Pond near its lower ee gregesio us in so’ 
mud in 1 foot of water, also in other parts of the same pond, and in Spot, Spy, and Horn Ponds, on sandy bottom, all 
near Boston, W. Boott ; Hammond’s Pond, W.G. Farlow; Concord Brook, gregarious, on firm yey H. Mann; 
Beaver Pond near Beverly, J. L. Russell ; Uxbridge, in Grafton Pond and several other ponds, J. W. Robbins. Ver- 
mont: Mt. oe in the Lake of the Clouds, C. G. Pringle, H. Mann, on gravelly bottoms, 1 to 2 feet deep; 
Lake Dunmore, A. W. Chapman. New Hampshire: Lake Winnipiseogee, in mud with Gratiola aurea, Eriocaulon 
etc., G. Engelmann ie specimens were the types ad Durieu’s I. Braunii), H. Mann, W. Boott; Echo Lake in the 
| es Mountains (where Mr. Tuckerman and myself had found J. lacustris), WV. Boott. Maine: Moose Lake on 
Kennebunk River, C. 7. Smith. Nova Scotia, Shelburne, T. P. James. Greenland, in the south, “Tessermint,” J. 
Vahl (perhaps this j is the kate I. echinospora ; I could not well analyze the small and poor specimen in my possession). 
Westward the species has been found in Western Canada (Ontario) near Hastings and in a lake northeast of Belleville, 
ona muddy bottom, J. Macoun. Michigan: Bellisle in Detroit River, H. Gillman. Utah: lake at the head of 
Bear River in the Uintah Mountains, at 9,500 feet alt., S. Watson ; this is the most western and highest, quite isolated, 
locality known to me. 
This form is most closely connected with the European type ; the leaves are perhaps not quite so finely taper- 
ing; stomata can always be found, at least near the tip of the leaf; the sporangia, white in the type, are spotted with 
brown sclerenchym cells ; the macrospores I cannot distinguish either in size or sculpture ; the microspores I find a little 
smaller. I may state here that the name of J. Brawnit is preoccupied, as it has already been given to one of the two 
species of the Tertiary deposits, the well marked spores of which have been discovered in the German Brown Coal strata ; 
Prof. Braun therefore proposed for our plant, if it should eventually be agi distinct, the name of I. ambigua. 
Var. Ropusta, Engelm., similar to the last, but much stouter, with 25 to 70 leaves, 5 to 8 inches long, with 
abundant stomata all over their surface ; velum covering about one-half of sos spotted sporangium; macrospores 
0.36 to 0.55 mm. thick, with the scileute of the last ; microspores the sam 
In Lake Champlain, on the north end of Isle is Motte, on a firm teen soil enn silt, in 1 to 2 feet of water, 
C. G. Pringle. Larger and stouter than any form of the last, but principally distinguished from it by the abundance 
of stomata. 
Var. Boorrit, Engelm. 1. c. Leaves erect, soft, bright green, fewer (12 to 20), short (4 to 5 inches long) ; sto- 
mata, mostly few, near the tip ; sporangia nearly orbicular, pale-spotted, 3 or more covered by the broad 
velum ; macrospores 0.39 to 0.50 mm. cpap tek ise longer and slenderer, delicate, generally iach, spinules; [381 (24) ] 
microspores 0.026 to 0.030 mm. long. — J. Boottii, A. Braun in litt. 
r Boston, in the Round Pond, cet 2 to 3 feet under water, and in the brook of Tofit Swamp, Lexing- 
ton, sometimes out of water, W. Boott. Very striking on account of the delicate green color of its soft leaves, and 
the long and slender spinules of the spores. ‘ 
Va r. MuRIcATA, Engelm. l.c. Leaves (15 to 20) long (6 to 12 inches), flaccid, bright green, with very few 
stomata ; sporangium broadly oval, pale-spotted, about half covered by the velum ; macrospores a little larger (0.40 to 
0.58 mm. thick), with shorter and more confluent, therefore sometimes almost crest-like spinules : macrospores slightly 
rough on edges, 0.028 to 0.032 mm. long. — I. muricata, Durieu 
he shallow and more rapid parts of Woburn Creek, and in : Aajona River, the main source of Mystic Pond, 
near vhs scattered over a clean gravelly bottom and always submerged, W. Boott. Remarkable for its long flaccid 
leaves and the shorter spinules of the macrospores, which form sometimes crests so that Durieu could compare it with 
I. riparia. 
5. I. Boranpert, Engelm. One of the smaller species, with erect, soft, bright green leaves tapering to a fine 
point, 5 to 20 or 25 in number, 2 to 44 inches. long, with thin walls and partitions, and generally not many stomata; 
sporangium broadly oblong, mostly without any spots, with a narrow velum ; ligula triangular; macrospores 0.30 to 
0.40 or rarely 0.45 mm. thick, marked with minute low tubercles or warts, rarely confluent to wrinkles ; microspores 
