3$4] TRANS, ST. LOUIS ACAD. SCIENCE. 2>J 
and dark gray .when dry; in some I find the warts much smaller than in 
others, but never wanting; microspores also quite dark brown. 
* * With peripheral bast-bundles. 
9. I. Engelmanni, A. Braun. Our largest species with numerous (25 
to 100) long (9 to 20 inches or more) light green leaves with abundant 
stomata; sporangium usually oblong to linear-oblong,.unspotted; velum 
narrow; ligula elongated from a triangular base; macrospores 0.40 to 0.52 
mm. thick, delicately honeycomb-reticulated ; microspores. 0.024 to 0.028 
mm. long, generally smooth.—Flora 1. c.; Am. Jour. 1, c.; Gray Man. L c. 
Var. gracilis, Engelm. Often submerged, with fewer (8 to 12) leaves, 
9 to 12 inches long; the bast-bundles sometimes quite small, or only two 
of them.—Gray Man. 1. c. 
Var. vAtiDA, Engelm. The stoutest of all our species; leaves 50 to 
100 or even 200, 18 to 25 inches long, keeled on the upper side; sporan. 
gium often linear-oblong (4 to 9 lines long), £ or often f or even f covered 
by the broad velum; macrospores rather smaller, 0.32 to 0.48 mm. thick; 
microspores 0.024 to 0.027 mm. long, spinulose,-—Gfay Man. 1. c. 
Var. Georgiana. Similar to the type; leaves few (in the only speci¬ 
mens seen 15, 10 to f2 inches long), rather Slender; oval sporangium with 
narrow velum ; macrospores larger, 0.48 to 0.56 mm. thick; microspores 
0.028 to 0.031 mm. long, smooth. 
In ponds and ditches, immersed in mud, rarely found in slow-running 
streams, in company with the ordinary vegetation of such localities, 
Bidens, Polygonum, Lycofius; Carices, Leersia, etc.; mature in summer; 
probably throughout the middle States, but thus far only found — from 
Massachusetts: Arlington brook, Alewife brook, West Cambridge brook, 
Woburn, Wm. Boott. Rhode Island : Newport, W. G. Farlo'W. Connec¬ 
ticut: Meriden, F. W. Hall— to New York: Peekskill, W. H. Leggett . 
New Jersey : E. Durand, C. F. Austin, and others. Pennsylvania, Beth¬ 
lehem, C. y. Moser, E. Durand , 6 1 . Wolle; Delaware Water-Gap, S. TV. 
Kni$e; Darby, y. G. Hunt; Philadelphia, E. Durand, C.E. Smith, and 
others. Delaware: Wm. M. Canby, A. Commons. Virginia: Salt Pond 
Mountain, with Parnassia asarifolia, W.M. Canby. Missouri: St. Louis, 
N. Riehl and G. Engelmann, 1842, in a single locality, where it was soon 
afteirWards destroyed by cultivation : not found otherwise west of the Alle¬ 
ghany Mountains. Var. gracilis seems to be a northern form : Brattle- 
borough, in Clark’s Pond, C» C. Frost; Colebrook’s, in a shallow stream 
With gravelly bottom, y. W. Robbins; New Haven, in fresh water on a 
tidal shore, D. C. Eaton; Newport, Bridges, G. Thurber; Passaic river, 
near low-water mark, y. Ennis. Var. valida was discovered in Pennsyl¬ 
vania near Warrior’s Mark, Huntington Co., and Smithville, Lancaster 
Co., T. C. Porter; and in Delaware. Wilmington, W.M. Canby. Var, 
Georgiana comes from a mountain stream, Georgia, the Horseleg creek, 
cm 
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