Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean: Vol. 2, Pt. 2

BOTANY.
Arn6tt under P. heterophyllus. The present single specimen resembles the var. z, in the narrow
and marginless sepals, and in the smaller flowers; but the peduncles are principally threeflowered. Not improbably it belongs to an entirely different species.
PENTSTEMON -HETERANDRUM (n. Sp.): glabrous; stem slender, virgate; leaves lanceolate or
oblong-linear, obtuse, callose-serrulate, obtuse or subauriculate at the base; panicle spicate,
interrupted; cymes subsessile, several-flowered; calyx puberulous, the segments ovate-lanceolate; corolla (nearly white) infundibuliform, slightly gibbous above, with 5 short subequal
lobes, in estivation various; stamens glabrous, straightish, of nearly equal length, all antheriferous, or the fifth without an anther. Sierra Nevada, California; June 30. Flower white,
with pink lines half an inch in length. Cauline leaves an inch long, and 3 lines wide; the
floral ones successively reduced to small bracts. Anthers glabrous; the cells distinct, moderately diverging. Stigma minute and simple. Ovary, &c., apparently as in Pentstemon.
Fruit not seen. Two peculiarities are to be noticed in this remarkable plant, either of which
would have been sufficient to exclude it from Pentstemon, but both prove to be inconstant in
the species. One of these relates to the stamens, which, in the flowers examined, were perhaps more frequently completely _pentand,2ous than otherwise; the fifth (posterior) filament
being similar to the others, and bearing either an exactly similar anther, or sometimes one
with rather smaller cells, and with the filament or connective prolonged into a short and blunt
apical appendage, as shown in figures 9 and 10. In some flowers, however, this anther was
found to be reduced to a single and rather imperfect cell, and a bare rudiment of the second
cell, as in fig. 11; in others again, (as in fig. 12 and fig. 6,) the fifth stamen is wholly destitute of any trace of anther, as ill Pentstemon universally, with this exception, if such it be.
It is also to be noted that the stamens of this plant are nearly equal in length, at least when
all five are antheriferous, and that they are inserted into the very base of the corolla. The remaining peculiarity relates to the cstivation of the corolla; in which, although some of the
flower-buds plainly have the two posterior lobes, or one of them, exterior to the others, in the
manner of the Antirrhinideve generally, (this being, indeed, the only absolute character of that
suborder), as shown in figures 3 and 4; yet, in quite as many instances we find the lateral
lobes exterior in the bud, and covering the two posterior as well as the anterior, (as is represented in figure 2), in the manner of the Rhinanthidee: a new and striking instance of
the instability of the modes of cestivation of the corolla, and one not altogether unexpected,
since Mr. H. T. Clark, a former pupil of Dr. Gray, and an acute and zealous naturalist, showed
him several years ago that both modes occur in Mimulus ringens, M. moschatus, &c.
MIMULUS LUTEUS, Linn. In the Sierra Nevada; June.
CASTILLEJA HISPIDA, Benth. in Hook. Fl. Bor.-.-mer. 2, p. 105. Cedar Mountains, south of
Great Salt Lake; May.
CASTILLEJA PALLIDA, Kunth. Foot of the Humboldt Mountains, on the eastern side; May.
AUDIBERTIA INCANA, Benth. in Bot. Reg. t. 1469; and in )DC. Prodr. 12, p. 359. On the
Sierra Nevada; June 20. Flowers blue.
MONARDELLA ODORATISSIMA, Benth. Lab. p. 332; and in DC. Prodr. 12, p. 190. p. GLABRIUSCULA; nearly glabrous; branches slender; leaves oblong-lanceolate, narrowed to a petiole at the
base, rather acute; heads terminal; bracts ovate, (colored,) shorter than the calyx, rather
acute; teeth of the calyx ovate-lanceolate, acute, unarmed. Sierra Nevada; July 8. Differs
from M. odoratissima in its larger and conspicuously petiolate leaves, and in the narrower
acutish bracts, &c. Flowers rose-colored.
Most of the species of this genus have the narrow lobes of the corolla sacculate at the apex;
a character which seems to have escaped the notice of Mr. Bentham.
MERTENSIA OBLONGIFOLIA, G. Don, Syst. Gard. 4, p. 372; DC. Prodr. 10, p. 92. Pulmonaria
oblongifolia, Nutt. in Journ. A4cad. Phil. 7. p. 13. Pass in Humboldt Mountains; May 23.
Flowers blue. This species was found also in various parts of Utah, by Colonel Fremont.
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