88 BOTANICAL GAZETTE. [ April, 
16. H. elliptieum Hook. Mostly Siaeaiiy 10 to 20 inches 
high: leaves elliptical-oblong, sessile or tapering at base, $ to 13 
inches long, 3 to 5 lines wide, pellucid- ir * with large seat- 
tered dots, translucently veiny: flowers 4 to 6 lines in diameter, 
in few-flowered cymes, the dichotomal flowers pedicelled: sepals 
mostly foliaceous and spreading, oblanceolate to narrowly obo- 
vate, usually shorter than the pale yellow petals: Cee as in 
164. 
the lak t.—FI. Bor.-Am. i 110; Torr. & Gray, FI. 
H. spherocarpum Barton, Fl. Philad. ii. 14, not Mic 
In moist ground, from Canada to Pennsylvania, westw: ae to the Winnipeg 
valley. 
Origin of the Flora of Indiana. 
HARVEY THOMSON. 
In an article of this nature it would not be advisable or nec- 
essary to enter into the details of the argument to prove that the 
original birthplace of our present flora is in the far north, near 
or even beyond the Arctic cirele. 
he origin of our present flora and the causes producing its 
present distribution present a rich field for thought and theory 
both to botanists and geologists, as the establishment of this the- 
ory of the northern origin of plants determines the temperature 
and climate of those regions in past geological periods. ae 
of the best thinkers of the botanical world have very ably dis- 
sussed this subject in their writings. Noticeable among these 
are Dr. Asa Gray, Sir Joseph Hooker, Sir W. sig De Can- 
dolle, Darwin, Wallace, Lesquereux, and others, Dr. Asa a Gray 
first advanced his the eory, before anything was known of the fos- 
sil life of the high northern latitudes, based upon the eBIDE 
resemblances between eastern Asiatic and eastern American 
e other writers have based their theories and conclusions me 
the identity of many fossil plants, found in the cretaceous rocks 
of Greenland and the extreme northern part of the continent, 
with those of temperate latitudes of both America and Asia. 
These fossil plants were found by Dr. Lyall, Sir John Richard- 
son and Sir Alexander Armstrong, and determined by Prof. 
Heer, of Zurich. There can, therefore, be no Boake as to the 
identity of these plants and, consequently, as to the origin of our 
temperate flora or the climate of those regions in the periods pre- 
ceding the tertiary, as it is conceded that plants become acclima- 
tized very slowly, if ever. During the glacial epoch chien plants 
