the day had kept the valley, which is sometimes rich and well timbered,
though the country generally is sandy. Mingled with the usual plants, a
thistle (_carduus leucographus_) had for the last day or two made its
appearance; and along the river bottom, _tradescantia_ (virginica)
and milk plant (_asclepias syriaca_) [Footnote: This plant is very
odoriferous, and in Canada charms the traveler, especially when passing
through woods in the evening. The French there eat the tender shoots in
the spring, as we do asparagus. The natives make a sugar of the flowers,
gathering them in the morning when they are covered with dew, and collect
the cotton from their pods to fill their beds. On account of the silkiness
of this cotton, Parkinson calls the plant Virginian silk.--_Loudon's
Encyclopaedia of Plants_.

The Sioux Indians of the Upper Platte eat the young pods of this plant,
boiling them with the meat of the buffalo.] in considerable quantities.

Our march to-day had been twenty-one miles, and the astronomical
observations gave us a chronometric longitude of 98 deg. 22' 12", and latitude
40 deg. 26' 50". We were moving forward at seven in the morning, and in about
five miles reached a fork of the Blue, where the road leaves that river,
and crosses over to the Platte. No water was to be found on the dividing
ridge, and the casks were filled, and the animals here allowed a short
repose. The road led across a high and level prairie ridge, where were but
few plants, and those principally thistle, (_carduus leucographus_,)
and a kind of dwarf artemisia. Antelope were seen frequently during the
morning, which was very stormy. Squalls of rain, with thunder and
lightning, were around us in every direction; and while we were enveloped
in one of them, a flash, which seemed to scorch our eyes as it passed,
struck in the prairie within a few hundred feet, sending up a column of
dust.