“32 Distinguishing Species of Populus and Fuglans [ January, | 
by interested me more; for they, observant of my approach, stood 
holding the oars of their rude skiff, eager to earn “dos reales” 
by transferring me to the opposite bank. I was not unwilling to 
avail myself of their services. Once on the Arizona side of the 
river, an hour’s walk would bring me to the thriving little town 
of Yuma, and my five days on the desert had well prepared me 
to appreciate the comforts of a well kept village hotel and the 
society of the civilized. 
“rT 
Vs 
THE METHOD OF DISTINGUISHING SPECIES OF _ 
POPULUS AND JUGLANS BY THE YOUNG 4 
NAKED BRANCHES} | 
BY PROF. W..J. BEAL. 
T is supposed to be the aim of the botanist when he describes — 
a plant to name the peculiarities which are the most striking 
and constant, especially those which are easily seen with the un- 
assisted eye. The writer has often been surprised that the pecu- — 
liarities of the pith, bark, leaf scars and buds of our deciduous 4 : 
leaved trees and shrubs are not more frequently given in descrip- 
tions. | @ 
For five or six months of each year most of these plants are 
destitute of flowers, fruit or leaves. If it is easy or possible to 
_ distinguish species by the points above named, it certainly would 
often be very convenient. In 1876, Frederick Brendel, of Peoria, 
Illinois, said :? “ We have no surer guide than the characters taken 
from the arrangement, form and construction of the buds, and in- 
many cases from the leaf scars.” 
I will now proceed to point out some of the differences between 
the species of Populus and of Juglans, as seen when the young 
growth is destitute of foliage. I have studied four species of | 
Populus and two of Juglans, all natives of Michigan. . 
Populus tremuloides—In very slender branches one year old all. 
of the pith is green; in larger branches a green layer surrounds 
the pith, which is of a whitish color much resembling the wood. 
With a short exposure to the air the pith becomes brown. 
The bud scales are polished. The transverse diameter of the 
1 Read at the Boston meeting of the American Association for the Advancement — 
of Science, Aug., 1880. 
ee pre eet ee 
_ *Bulletin of the Illinois Museum of Natural History, No. 1, page 26. 
