484 PROCEEDINGS OF THE AMERICAN ACADEMY. 
em. long, 2 to 5 mm. broad, narrowed below into a short petiole, obtusish 
or acute at the apex, closely appressed-pubescent on either surface, mar- 
gins revolute: flowers axillary,, solitary, scattered along the branches 
from near the base: calyx-divisions lance-linear, acute, about 3 mm. long, 
slightly unequal: corolla when fully expanded, 8 to 10 mm. broad ; tube 
about equalling the divisions of the calyx; lobes,rounded: nutlets about 
1 mm. long, slightly hirtellous on the outer upper surface. — Collected by 
C. G. Pringle on plains near Tehuacan, altitude 1540 m., 29 July, 1897, 
no. 6749, es 
Most nearly related to H. Pringlei, Rob., from which it is distin- 
guished by the more closely appressed pubescence, the less unequal 
lobes of the calyx, and also by the more rounded lobes of the corolla. 
Heliotropium mexicanum. Suffruticose: stems ascending oF 
erect, 8 dm. or more high, usually much branched, covered below with a 
brownish pubescent bark, which gradually peels away from the stem, the 
stems above and also the branches covered with a rather dense reflexed 
pubescence, and with scattered ascending stiffer hairs intermixed : leaves 
alternate, short-petiolate, oblong-oblanceolate to narrowly lanceolate, in- 
cluding the petiole 1 to 5 cm. long, 2 to 8 mm. broad, the upper surface 
hirsute-hispid or sub-strigose with shorter finer hairs intermixed, some- 
what channelled by the sunken midrib and lateral nerves, rather densely 
and finely pubescent beneath with scattered hirsute hairs intermixed 
especially upon the raised midrib and arched lateral nerves, obtuse OF 
acute, margin entire, revolute: petioles about 1 mm. long: inflorescence 
in lateral and terminal usually pedunculate false racemes, either simple or 
in pairs, 2 to 20 cm. in length: flowers sessile or short pedicellate, bracte- 
ate: bracts small, subulate, about 2 mm. long: calyx 3 to 4 mm. long, 
deeply 5-parted; divisions somewhat unequal, linear-oblong, obtuse oF 
occasionally acutish, hirsute-pubescent: corolla white, 5 to 6 mm. long, 
equally broad when fully expanded, shallowly 5-lobed or pentagonal, 
somewhat plaited, strigosely pubescent on the outer surface; tube slightly 
exceeding the calyx-lobes: stamens inserted at the middle of the corolla- 
tube: nutlets enclosed by the persistent calyx, about 1 mm. long, hirsute 
pubescent. — Collected by Prof. A. Dugés near Guanajuato in 1880 
(without number); Dr. Edward Palmer, Southwestern Chihuahua, 
August to November, 1885, nos. 31, 98; Rev. Lucius C. Smith at 
Cnicatlan, Oaxaca, altitude 554 m., 24 September, 1894, no. 209, and 
at Las Sedas, altitude 1780 m., 27 June, 1895, no. 391; C. Alvarez, 
Valley of Elta, Oaxaca, September, 1895 (L. C. Smith’s collection), " 
750; Dr. Edward Palmer on Iron Mountain near the city of Durang® 
