FISSION OF LEAVES. 63 
the leaves of which latter thus resembled those of Urtica 
biloba, which are habitually bilobed at the summit. M. 
Clos' mentions an instance where the terminal leaf and 
first bract of Orchis sambucina were divided ‘into two 
segments. The same author also mentions the leaves 
of Anemiopsis californica, which were divided in their 
upper halves each into two lobes—also leaves of a lentil 
springing from a fasciated stem and completely divided 
. into two segments, but with only a single bud in the 
axil. ‘The axillary branches in hke manner showed 
traces of cleavage. Fig. 26 represents a case of this 
kind in Lamium album, conjoined with suppression of the 
flowers on one side of the stem. I have alsoin my her- 
barium a leaf of Arwm maculatwin, with a stalk single at 
the base, but dividing into two separate stalks, each bear- 
ing a hastate lamina, the form of whichis so perfect that 
were it not from the venation of the sheath it would 
be considered that there was here a union of two leaves 
rather than a bifurcation of one. A garden Pelar- 
gonium presented the same appearance. 

Fic. 27.— Bifureated leaf of Pelargonium. 
Fern fronds are particularly liable to this kind of 
subdivision, and they exhibit it in almost every degree, 
from a simple bifurcation of the frond to the formation 
of large tufts of small lobes all formed on the same 
plan by the repeated forking of the pinnules. These 
may be considered as cases of hypertrophy. 
Moquin-Tandon, at a meeting of the Botanical Society 
' *Mém. Acad. Scien. Toulouse,’ 5th series, vol. iii. 
