464 THE GENUS ISOETES IN NORTH AMERICA. 
0.026 to 0.031 mm. long, generally spinulose : rarely, in the Rocky Mountain form, smooth, deep brown. — Am. Nat- 
uralist, 8, 214. — I. Californica, Engelm., name only in Gray, Man. 1. ¢. 
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, 9,000 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 1 or 2 feet of water,” H. Bo- 
lander ; Ice Lake, near Soda Spring station, 7,500 feet alt., with Menyanthes trifoliata, Engelmann; in many lakes of 
the high sierras, reported by A. Kellogg; on Mt. Adams, Washington Terr., W. N. Suksdorf; in the soft muddy bot- 
tom of a shallow pond near the falls of the Yellowstone River in Wyoming, nearly covering the muddy bottom, partly 
emerged near the banks, (. C. Parry; in a subalpine lake at Alta, Wahsatch Mountains, Utah, M. HE. Jones, and ina 
lake in the Gunnison region, Western Colorado, covering ten acres of ground with Menyanthes, T. 8. Brandegee. —. 
This species has much the appearance of I. echinospora, var. Boottii, with its soft, bright green leaves ; the stomata are 
often difficult to make out. 
B. Amphibious, partially emerged, submerged only in the earlier period of their growth or temporarily ; a (25)] 
stomata always present. 
* Without peripheral bast-bundles ; intermediate between the submerged and the truly amphibious species. 
t+ Velum partial. 
6. I. saccHarata, Engelm. A small plant, usually with a flat, depressed trunk; leaves subulate, olive-green, 
spreading, 10 to 20 in number, 2 to 3 inches long ; sporangium oblong, spotted, with a narrow velum ; ligula triangu- 
ar ; ores 0.40 to 0.47 mm. thick, covered with ie minute distinct or sometimes a little confluent warts ; 
microspores papillose, 0.024 to 0.028 mm. long. — Gra A i 
n the banks of the Wicomico, below Salisbury, and of the Nanticoke rivers which empty into the Chesapeake 
Bay, pron shore of Maryland, above salt water, scattered on a thin stratum of mud covering a bed of gravel, over- 
flowed by the tides, in company with Sagittaria pusilla, Eriocaulon, Tillea simplex, Micranthemum Nuttallii, etc., 
W.M. Canby. The trunk is in this species unusually flat, about half as thick as it is wide in the direction of the 
groove ; about one inch of the base of the leaves is pale, and covered with mud agitated by the tides, the upper part is 
olive-green and when out of water apt to be borne down by mud ; stomata abundant ; macrospores as if sprinkled over 
with minute white grains of sugar, whence the name. 
7. I. nrparta, Engelm. A larger plant with slender but rather rigid deep green leaves (about 15 to 30 in num- 
ber), 4 to 8 inches long, rarely longer; stomata numerous, dissepiments thick, consisting of about 4 layers of cells ; 
sporangia mostly oblong, distinctly spotted by groups of brown sclerenchym cells, } or rarely } of it covered by the 
velum ; macrospores among the largest, 0.45 to 0.65 mm. in diam., marked with jagged crests isolated, or anastomo- 
sizing, especially on the lower surface, which thus becomes somewhat reticulated ; microspores more or less tubercu- 
lated, 0.028 to 0.032 mm. long.— Flora, Regensb. Mar. 31, 1846; Am. Jour. Arts & Sci. 3, p. 52, 1847; Gray, 
oe 
On the banks of the lower Delaware River between the limits of the tides in mud covering gravel, from Burling- 
ton, T. A. Conrad, to Wilmington, W. M. Canby, and especially about Philadelphia, where Nuttall first discovered 
oa de S. re E. Durand, and the later botanists have serene. collected it, associated with Elatine, Limosella, 
m, Sagittaria pusilla, ete. ; also in millponds and still parts of streams in New England, Uxbridge, J. W. 
ae grec C. C. Frost, and northward, maturing in pov and September. = hee I. lacustris, with 
leaves as dark green and almost as rigid, and with spores approaching it in size and sculpture, but readily distinguished 
by its stomata and by the spots on the sporangium; from J. echinospora, var. Braunii, with which smaller forms it may 
possibly be confounded ; it can always be known by the darker, stiffer leaves, and especially by the char 
acter of the spores. Some of the Uxbridge specimens, entirely submerged 2 to 4 feet deep in water, kee [383 (26) ] 
slenderer and longer (even 12 inches) leaves. The trunk, mostly thick, I have once found 3-lobed. 
Germinating spores and young plantlets were found in June by Mr. Durand, indicating germination in spring and 
early summer. 
Farther northward, in Maine, J. 1. Chickering, and in Canada West, Crow River, Hastings Co., J. Macoun (here 
in running water with Brasenia and Potamogeton), a form occurs with very few stomata on leaves ae apparently two 
weak bast-bundles, an upper and a lower one, very pale spots on the sporangia and smoothish microspores. This 
might be designated as var. Canadensis, but too little is known about it as yet to form a definite opinion. 
* 4, I. saccHARATA, Engelm.,n. sp. Leaves (10-15, 2-3 berculate ; microspores (0.012 line long) papillose. — On Wi- 
inches long), oe olive-green, curved ; sporocarps small, comico River; eastern shore of Maryland, between high and 
ovoid, oy pper edge covered by the velum, nearly low tide, W. M. Canby.” — (From Gray’s Manual, 5th ed. 
« cdneue ee (0.20-0.22 line wide) minutely tu- 1868, 676). — Eps. 
