EO 
THE GENUS ISOETES IN NORTH AMERICA. 461 
3 a 4 : EG: g 
ad N = 
galelelelslé le ae ee 
Sh e/eleleiSlalalglelzlelflelel lily g Ei¢ 
eel ele ele l2lele/slalelalsieisieleleietsigialaie 
~ $ 2 a) = = = ° = = 
SRST SLES (SLES) ES Sl ELELSTES S/S sll Slaslslsis 
Bs. Hs poe one rs ae am ee ee eS pong ig e ag fag 
PROOMIAMIS cccosrssarmancncth Mo [bstcdidl verees last ead A tien ces | “eee | cate f- | me |: Rape! | nace’ ees |, | | 
INNO RUNNER oc cubivecaxensh LAN sacs bon cies Sorkcanel | eee | | ve ees 
EG cc ccnlptembesvuxis! 2 aoa sesefoeeel ote see eee | | | | 
New Hampshire ......... 2 Lo bssidinatsyce Vhs, ; | | | | 
Vermon me ‘ page Wan) eres Ss eee, Petree! Geeta iE; eee: ee 1 | | | seas 
Massachusetts 1 1 ee Se ete 1 13:4 Eeswiel 
Rhode Island cu-g ORS PCN AE 
Connecticu peas SS, Berar. 1 | i Waa ces 
ew Yor | eS SG Va 1 | ABORT Neen 
Ontario ot oe ae | | 
Michiga ans (aes, | | | a Sue: 
Pennsylvania Eee Bea 2 Bae: Bsc 1 | 
New Je ee bea | 1 7-4 | 
Delawai Bea ry ea ie Canes 1 | 
Maryland bon 1 | 
Virginia Lgl 1 | eal RRS BERGE. Bes Pee 
Georgi LSet TB irene aide ete 1 | | 
Florida ee a ee | 
Tennessee a ee | | Y tsehc: 
Illinoi ee | i BRE WSs, Pea IS Si 
Iowa | | | 2) ee 
Missouri } | 1 Pam, AI ERR MR) evel POeen 
Indian Territory she ee DeLee Miscapeseal 
exas aR ea, Ine Seen Nees Cesar AY ear: Ce here 
ee 1 Bees ee ee nites eaenn 
RE ean ee 1 crsefoseee foe ie DS! | Pate ae aaa 
1 
Td ano vee gaesccsieecceee| VL [ferseefovseeefersee| vee | : 
ashingion Territo 2 be) Reerens beeen freee peremes cereers pererny ertenr] cretery errere) (errs) certcn eececny cerenws Meee boners 
Oregon ese sneesesccsee otk | a i 5 tee 
California scribes Aenvacad Stas 1 1 j 1 
] } ee | 1 
Pet 
oO Tr Ss 3 oe . § Lr a t setts. 
Fie oh elpcees * “ eg Penasrnin aud sey 7 ersey. 
8 “fe oe «“e oe “ 
9. 8 - i = 10 Stakes, Territories, or Provinces. 
1 “ ““ “ “ “ 15 States, errito’ or Provinces. 
§ 6. ENuMERATION OF THE SPECIES. [377 (20)] 
1, Trunk BILoBeD. 
A. Submerged, normally growing under water, only in unusually dry seasons coming above the surface; leaves quad- 
rangular, without peripheral bast-bundles; velum incomplete. 
* Without stomata. 
1. I, tacustris, Zinn. Leaves stout, rather rigid, obtusely quadrangular, acute but scarcely tapering, dark 
or olive-green, 10 to 25 in number, 2 to 6 inches long; sporangium orbicular to broadly elliptical, not te ge 
yather narrow velum; ligula triangular, short or somewhat elongated; macrospores 0 in diameter, 
marked all over with distinct or somewhat confluent crests ; microspores = 0.035 to 0.046 mm. fos the longer 
diameter. — Syst. Veg. I. 1753 ; Durieu, Bull. Soe. Bot. eines: 8, p- 164, 1861; Gray, Man. ed. 5, p. 675. 
ar, PAUPERCULA with fewer (10 to 18), thinner, shorter (2 to 3 inches) eases and smaller spores (macrospores 
0.50 to 0.66 mm. diam.; microspores somewhat granulated, 0.026 to 0.036 mm ). 
A northern species of Europe and America, generally gregarious on gravelly soil in the bottom of lakes under 
1 to 4 or 5 feet of water, farther south only on mountains; maturing in September and October. Catskill Mountains, 
N.Y., Schweinitz ; Echo Lake, Franconia Mountains, N. H., Tue Engelmann; in Massachusetts, in Fresh 
Pond, near Cambridge, W. Boott, and Uxbridge, J. W. Robbins ; Brattleborough, Vt., €. C. Frost ; Saulte de Ste. Marie 
n Lake Superior, Porter and Leidy. The variety in Grand Lake, Middle Park, Colorado, over 8,000 feet alt. » Engel- 
mann, and in Castle Lake, near Mt. Shasta, California, 7,000 feet alt., C. @. Pringle. —'This is the original Linnean 
species, formerly confounded with others, and first clearly established by Durieu, 1. ¢. It is always readily recognized 
by its rigid, rather thick, not gradually tapering dark green leaves, which do not collapse when taken out of the water, 
and by the size and sculpture of the spores. The variety paupercula is based on western mountain specimens, and is 
characterized by the smaller proportions of all parts, and especially of the (for the species) unusually small micro- 
5 I adopt, for the smaller measurements, the metrical system, which will gradually but surely supersede the old and 
clumsy method ; while, in the larger measurements, as the length of leaves, I still adhere to the foot and inch as the one yet 
best understood. The millimetre is, as is well known, equa] to very nearly half a line. 
