ENGELMANN THE GENUS ISOETES IN N.AMERICA. 381 



delicate, generally simple spinules; microspores 0.026 to 0.030 mm. long. 

 — /. Boottii, A. Braun in litt. 



Near Boston, in the Round Pond, Woburn, 2 to 3 feet underwater, and 

 in the brook of Tofit Swamp, Lexington, sometimes out of water, Wvi. 

 Boott. Very striking on account of the delicate green color of its soft 

 leaves, and the long and slender spinules of the spores. 



Var. MURiCATA, Engelm. 1. c. Leaves (15 to 20) long (6 to 12 inches), 

 flaccid, bright green, with very fewstomata; sporangium broadly oval, 

 pale-spotted, about half covered by the velum; macrospores a little larger 

 (0.40 to o.5Smm. thick), with shorter and more confluent, therefore some- 

 times almost crest-like spinules : macrospores slightly rough on the edges, 

 0.02S to 0.032 mm. long. — /. muricata, Durieu 1. c. 



In the shallow and more rapid parts of Woburn creek, and in Abajona 

 river, the main source of Mystic Pond, near Boston, 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 /. 

 rip aria. 



5. L BoLANDERi, 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 

 4i inches long, with thin walls and partitions, and generally not many 

 stomata; sporagium 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 0.026 to 0.031 mm. long, generally spinulose; 

 rarely, in the Rocky Mountain form, smooth, deep brown. — Am. Natural- 

 ist, 8, 214. — /. Californica Engelm., name only in Gray Man. 1. c. 



A western mountain species, found gregarious in ponds and shallow 

 lakes of the Sierra Nevada of California, northward to the Cascades and 

 eastward to the Rocky Mountains : in little pools on meadows in the upper 

 Tuolumne valley 9,coo to 10,000 feet alt., on Mt. Dana, on the Mono trail, 

 in Mary's Lake near the summit, 7,000 feet alt., in small lakes about 

 Cisco 4,500 to 5,000 feet alt, " mostly gregarious in mud covering gravel, 

 in I or 2 leet of water," H. Bolander ; Ice Lake, near Soda Spring station, 

 7,500 feet alt., with Menyanthes trifoliata, Engehnafin ; in many lakes of 

 the high sierras, reported by A. Kellogg; on Mt. Adams, Washington 

 Terr., W. N. Siiksdorf, in the soft muddy bottom of a shallow pond near 

 the falls of the Yellowstone river in Wyoming, nearly covering the muddy 

 bottom, partly emerged near the banks, C. C. Parry: in a subalpine lake 

 at Aha, Wasatch Mountains, Utah, M E. Jones, and in a lake in the 

 Gunnison region. Western Colorado, covering ten acres of ground with 

 Menyanthes, T. H. Brandegee. — This species has much the appearance of 

 /. echinospora var. Bootti, with its soft bright green leaves ; the stomata 

 are often difficult to make out. 



