464 PROCEEDINGS OF THE AMERICAN ACADEMY. 
* * * Leaves elliptic to oblong-ovate, usually 3-nerved from the base, bearing a 
single large gland or cluster of glands on the lower surface at the tip 
+ Leaves distinctly 3nerved, margins strongly revolute. 
16. G. hypadenium, Scuaver. Suffrutescent: stems prostrate 
or ascending, glabrescent, often leafless and little branched below, cov- 
ered with a thin grayish bark which later separates from the stem, freely 
branching above; branches tetragonal, pilose-hirsute: leaves sessile, 4 
to 10 mm. or more long, nearly one half as broad, obtuse, usually hirsute- 
pubescent, more or less glabrate above, rather densely white-pilose of 
merely hirsute beneath, margins ciliate: corolla 4-parted, about 2 mm. 
in diameter; lobes externally pubescent with rather long hairs: fruit 
about 2 mm. in breadth; carpels somewhat separated at maturity. — 
Linnea, xx. 700. G-. leucotrichum, Hemsley, Biol. Cent.-Am. Bot. il. 
65, & v. t. xli. figg. 4-6.——Orizaba, Miiller, nos. 174, 1218, Sumichrast, 
no. 514; Puebla, dry limestone ledges near Tehuacan, altitude 1540 m., 
27 August, 1897, Pringle, no. 6694; Guerrero, between Chilopa and 
Tixtla, altitude 1540 to 2150 m., 17 December, 1894, Z. W. Nelson, 
no. 2166; Jalisco, near Guadalajara, Pringle, 5046. 
17. G. fuscum, Marr. & Gat. Perennial: stems tetragonal, be- 
coming more or less scabrous along the slightly thickened angles, the 
younger stems and branches bearing scattered pilose-hirtellous slightly 
curved hairs: leaves elliptic-oblong, 0.5 to 1.5 em. long, 2 to 5 mm 
broad, short-petiolate, submucronate or merely acute, glabrous or spa! 
ingly hirsute above and upon the nerves beneath, conspicuously glandular- 
punctate; margins usually ciliate: inflorescence cymose-paniculate : 
flowers brownish purple ; lobes of corolla commonly pubescent. — Bull. 
Acad. Brux. xi. i. 126; Walp. Rep. vi. 13; Hemsley, Biol. Cent.-Am- 
Bot. ii. 64. — Oaxaca, Cerro de San Felipe, Galeotti, no. 2633, dry hills 
near the City of Oaxaca, altitude 1845 m., Pring/e, no. 4795 (distributed 
as G. uncinulatum, DC., var. abstipum, Watson), near Reyes, altitude 
1750 to 2000 m., #. W. Nelson, no. 1774; Guanajuato, Duges. 
+ + Leaves indistinctly 3-nerved, margins little or not at all revolute. 
18. G. hystricocarpum. Stems usually many from a perennial 
base, ascending, more or less branched above, covered with a spreading 
pilose-hirsute pubescence: leaves elliptic-oblong to oblong-lanceolate, 
5 to 12 mm. long, 2 to 7 mm. broad, short-acuminate or submucronaté 
hirsute on the upper surface and upon the midrib and inconspicuous 
ateral nerves beneath: flowers white, somewhat cymose-paniculate = 
_ terminating the lateral branches in few-flowered cymes: lobes of the 
corolla covered externally with a few long pilose hairs. — Cool cliffs and 
