435 
very large stipules resembling those of P. Plattensis and a large 
calyx which is strongly hirsute. From P. Plattensis and the other 
species of the group it differs in the stoutness of the plant, which 
is 3-6 dm. high and by the fewer (2-5 pairs) and larger leaflets, 
which are from 3-6 cm. long, and the acute teeth. It is a rare 
Species. The only specimens seen are the following : 
' Washington : W.N. Suksdorf, no. 539. 1875. 
Oregon: Elihu Hall, no. E35. 1878, 
California : J. G. Lemmon, no. 1200. 1875. 
British Columbia: John Macoun, no. 32. 1890. 
Rocky Mountains of British America: E. Bourgeau, 1858. 
Phyllotaxy as a Guide to Plant Analysis. 
By A. L. BENEDICT. 
There are few discrepancies in teaching more striking than the 
Contrast between the elaborate discussion of leaf-arrangement in 
nearly all text-books and courses on Organography and the neg- 
lect of the subject in practical analysis. 
Omitting the leaves of cryptogams and the coniferae, two 
methods of arrangement are found, the verticillate or whorled and 
_the spiral, alternate or scattered. The words verticillate and 
Whorled are really the same, if we seek their root. The term scar- 
tered is highly objectionable, since it suggests that the leaves occur 
haphazard, but nowhere in botany is a more exact mathematical 
System followed than in the putting forth of leaves. The term 
alternate should, from its meaning, be limited to the simplest va- 
riety of spiral phillotaxy, in which the leaves occur, first on one 
Side and then on the other, of the stem. 
If we conceive the outer layer of the stem to be made up of a 
Number of columns of cells, we have a simple and lucid explana- 
_ tion of the decussation of adjacent whorls and of the spiral line in 
Which leaves are otherwise thrown out. The development of a 
leaf involves a tremendous expenditure of vitality and it is easy to 
understand why one whorl of leaves should issue from the columns 
Which have rested during the formation of the preceding whorl, | 
