179 
Euphorbia serpyllifolia Pers. Syn. PI. ii, 14 (1807). 
Only a small specimen collected on the railroad embankment near Mullen, July 
24, This seems to be nearest the variety consanguinea, but the material is too meager 
to decide (No. 1833). 
Euphorbia glyptosperma Engelm. Bot. Mex. Bound. ii, 187 (1859). 
Very variable. Some forms are prostrate and spreading, with broad leaves 
resembling those of /£. geyeri, except that they are slightly toothed near the apex: 
Thedford, June 18; Forks of Dismal River, July 12; Mullen, July 18; Forks of 
Middle Loup, July 27 (No. 13873). Another form has narrower, that is, oblong, leaves 
and ascending stem: Forks of Dismal River, July 11; northeast of Whitman, August 
4; Mullen, July 19 and September 16 (No. 1527). A third form, collected at Thed- 
ford, September 9, is upright and slender, and has very narrow leaves (No. 1742), 
Euphorbia hexagona Nutt.; Spreng. Syst. iii, 791 (1826). 
Sand hills: Mullen, July 17 and September 16 (No. 1545). 
Croton texensis (Klotzsch) Muell, Arg. in DC. Prodr. xv, 692 (1866); Hendecandra 
texensis Klotzsch, in Erichs. Archiv. i, 252 (1841). 
Common in the sand hills: Thedford, June 17; Dismal River, July 29; Plummer 
Ford, July 3; Forks of Dismal River, July 12; Mullen, July 22 (No. 1430). 
ULMACE 4. 
Ulmus americana L. Sp. Pl. i, 226 (1753). 
This was collected only in leaf, on the banks of South Dismal River, July 13. 
Some of the trees were of the common form with smooth twigs (No. 1540). Others 
had the young twigs pubescent, as in U. fulva, otherwise agreeing fully with U. 
americana (No, 1541), The first form was known as white elm, the latter as water elm. 
Celtis occidentalis L. Sp. Pl. ii, 1044 (1753). 
Here and there on the hillsides near the rivers and on the banks: Norway, June 
23; Dismal River, July 11 (No. 1410), At the last place I found trees about 0.5 m. 
in diameter. “ 
URTICACES. 
Humulus lupulus L. Sp. Pl. ii, 1028 (1753). 
Forks of Dismal River, Juiy 13; but neither flowers nor fruit were seen (No. 1589), 
Urtica dioica L. Sp. Pl. ii, 984 (1753). 
A slender plant with thin, broadly cordate leaves, which I take to be a form of 
this species, although the leaves are not at all downy beneath. Flowers are wanting 
(No. 1790). 
Urtica gracilis Ait. Hort. Kew. iii, 341 (1789), 
Very variable. One form collected has narrow, sharply serrate, short-petioled 
leaves, which are bristly along the veins and on the petioles; flower cluster short. 
Collected 20 miles south of Whitman, August 4; Plummer Ford, August 23 (No. 
1821), Another form is similar except that it has broader leaves and longer petioles 
and peduncles: Mullen, July 17 (No. 1558), The third, with narrow leaves and 
F slender peduncles, is the most common form: Plummer Ford, July 4 and August 22; 
Mullen, September 16 (No. 1520). 
Adicea pumila (L.) Raf. Ann. Nat. 179 (1815); Urtica pumila L. Sp. PL. ii, 984 
(1753). 
Mullen, July 27 and August 19; South Dismal River, August 12; Thedford, Sep- 
tember 7; west of Whitman, September 19 (No. 1609). 
. Boehmeria cylindrica (L.) Willd. Sp. Pl. iv, 340 (1805); Urtiea cylindrica L. Sp. 
Pl. ii, 984 (1753). 
Wet meadows, among bushes: Halsey and Natick, September 11 (No, 1745). 
