eects 
ee 
sineenuineaic ioe 
ad 
a | 
90 Braun and Engelmann’s North American Equiseta. 
evidently 4-carinate leaves; their points less deciduous, sphace- 
late, nearly smooth.—F.. aledbenin; Schleicher. 
y. TRacHyopon, A. Braun.—Stem smaller ; carine more plain= . 
ly with two rows of tubercles, which are separated by a furrow; — 
sheaths with a black limb, consisting of about ten evidently 4-ca- 
rinate leaves, their points less deciduous, whitish or sphacelate, — 
rough on the back. 
Hab. Europe, with all the varieties; in North America, only 
the common form has yet been remarked: Pennsylvania, (Muh- — 
lenberg, Schweinitz,) Canada and Northern States, (Beck’s Bot- | 
any, §c.,) Michigan, (H’ngelmann,) to Kentucky, (Short. ) Both» 
varieties will doubtless be found in this country. 
Specimens from the sandy shores of Manitou Island, Lake Mi- | 
chigan, have in the fertile stems 24 to 26 carine, (in the smaller 
sterile ones 17,) with nearly one row of tubercles; the black — 
limb of the sheath is somewhat indistinct ; leaves with 4 or some- — 
times (by obliteration of the carinal fariow) only 3 carine; teeth — 
white, less deciduous, leaving a more exactly truncate margin. © 
Specimens from Kentucky have 20 to 28 carine ; tubercles nearly — 
in one row; leaves with 4 or only 3 carine; very near E. robus- | 
tum, 7. ifine: ! Var. y. is by far the ecuigliedt form ; by its small- 
er size, and plainly 2-rowed tubercles on the caring, it approaches — 
to £. variegatum. E. hyemale is a northern plant, being re- | 
placed towards the south in North America, by the larger E. ro- | 
bustum, and in Europe by a smaller species, the much-confoun- | 
ded £. elongatum, Willd., (EZ. ramosum, Schleich., E. panno- | 
nicum, Kit., EL. Illyricum, Hoppe, etc.,) which extends from 
Southern Gertiauy. through the whole of Southern Europe to- 
Northern Africa, Arabia, and middle Asia, and a variety of which 
occurs again at the Cape of Good Hope, Isle of Bourbon, and Isle 
of France: but it has not yet been met with in ‘enoriea: 
Bg 
10? E. poreate, Bongard.—Found in Sitcha on the North- _ 
west coast by Dr. Mertens, is unknown to me; perhaps a variety 4 
of E'. hyemale? (A. Brine.) 
11. HE. varircatum, Schleicher.—Cespitose; stems low, simple 
carinz rough with two rows of tubercles, separated by a furrow 
the grooves larger and deeper than the furrows, on each side with 
a single series of stomata; vallecular air-cavities of the same widtt 
as the central cavity, the carinal ones very small; sheaths some- 
what campanulate, variegated with black, constaciiae of about 
