ENGELMANN—NORTH AM. SPECIES OF JUNCUS. 475 
central States of the Mississippi Valley, to which it seems 
to be a stranger. It flowers in July and August, when 
J. acuminatus, with which it might be confounded, has al- 
ready shed its seeds.—Var. a is decidedly the most north- 
ern form of this species, which extends from the north- 
eastern States to Canada and the Lake Superior region, 
Hb. n. 76 & 77, and southward to Pennsylvania, where 
Prof. Porter finds it in the neighborhood of Lancaster; Dr. 
Chapman gives Georgia as the southern limit of “J. acumina- 
tus,” but I have seen no specimens from those southern parts. 
—Var. ? has been observed from Pennsylvania, Porter, to 
western New York, Gray, Sartwell, Vasey, Clinton, Central 
Ohio, Swlivant, Central Illinois, Hall, Brendel, Michigan, Bige- 
low, Hb. n. 79, and Wisconsin, Lapham.—Var. y is a form of 
the Atlantic States, found from Connecticut, Eaton, to New 
Jersey and Pennsylvania, Durand, Smith, Hb. n. 81, Leidy, 
Porter, Hb. n. 80, Delaware, Commons, Hb. n. 82, District of 
Columbia, Bebb, South Carolina, Nuttall, and Georgia, Beyrich 
(distributed by him under the name of J. acuminatus).—V ar. 
6 is the most common of all the form’, extending over the 
whole region, with the exception, perhaps, of its north-east- 
ern extremity. I have not seen any specimens from Canada, 
or from the States north of Massachusetts. ‘The Herb. norm. 
contains different forms of this variety from Michigan 84, 
Pennsylvania 83, Maryland 88, and South Carolina 85, 86 
and 87. 
The different forms of this intricate species are as wide 
apart in habit, as well as in artificial characters, as they pos- 
sibly can be, but are connected by insensible. transitions, so 
that even the different varieties cannot always be kept clearly 
distinct. Its synonymy is in some confusion. It is quite im- 
possible that specimens of so wide-spread and so easily accessi- 
ble a species should not have been obtained by collectors long 
since, and we do indeed find such among Michaux’s (La Harpe, 
l. c.) and among Schweinitz’s plants, and no doubt in many 
other old herbaria; but, somehow or other, its striking diag- 
nostic characters were overlooked, and it was thrown together 
with other species, such as the similar looking J. acumanatus, 
especially its var. legitimus, under the name of J. polycephalus 
or J. verticillatus (lege subverticillatus )—This and the follow- 
ing two species are well distinguished from all the other 
articulate ones by their tailed seeds and by the proportions 
of their usually strongly nerved sepals, the inner of which 
always exceed the outer ones. From its two allies it is dis- 
tinguished principally by the shape and proportion of its cap- 
sule, and the smaller and differently shaped seeds. 
Varr. a and # are distinguished from the others by their 
small, usually 3-4-flowered, heads, smaller flowers, which are 
14-1} and only in Lake Superior specimens of a 12 lines long, 
[April, 1868.] 81 
