FISSION OF LEAVES. 65 
glabra wherein the blade of the leaf on one side was 
deeply and irregularly laciniated, the other side re- 
maining entire. (Verhandl., d. 35, Naturvorschef- 
versamlung, tab. 3.) Lacimiate varieties of plants are 
of fr equent occurrence in gardens where they are often 
cultivated for their beauty or singularity; thus, there 
are laciniated alders, fern-leaved beeches and limes, 
oak-leaved laburnums, &c. <A list of several of fhiese 
is subjoined. A similar fission takes place constantly 
in the cotyledons of some plants, sometimes, as in 
Conifere, to such an extent as to give an appearance 
as if there were several cotyledons.’ 
It is not always easy to recognise, at a first glance, 
whether the division be the result of disunion or of an 
incomplete union of two leaves, but we may be guided 
by the number of leaves in the cycle or the whorl. 
The number is complete in cases of partial disjunction, 
while in cases of fusion it is complete. Again, in in- 
stances of disjunction, there is only one point of origin, 
but, when two leaves are grafted together, two such 
points may generally be detected at the base of the 
leaf, or a transverse section of the leafstalk will show 
indications of fusion. The number and position of the 
midribs will also serve as a guide, as in cases of fusion 
there are generally two or more midribs, according to 
the number of fused leaves ; but as Moquin well remarks, 
this latter character cannot be always depended upon, 
for the median nerve may divide without any corre- 
sponding separation of the cellular portions of the leaf. 
The author just quoted cites examples of this kind in 
Cardamine pratensis, Hedera Helix, Plantago major, 
Geraniwm nodosum. 
The following list of plants commonly producing 
leaves that are cleft or divided, to a greater extent than 
is usual in the species, is mainly taken from one 
given by Schlechtendal, ‘ Bot. Zeit.,’ 1844, p. 441, 
with additions from other sources. The ! indicates 
that the author has himself met with the deviation in 
1 Duchartre, ‘ Ann. Se. Nat.,’ 3rd series, 1848, vol. x, p. 207. 
i) 
