544 
MORPHOLOGY. 
BOOK VI. 
and many culinary plants have undergone a similar change ; 
while the common hemp has sported into a gigantic variety 
twice the usual size. The stem occasionally becomes fasciated ; 
that is to say, assumes the appearance of a number of separate 
stems, glued together side by side, as in the common cocks- 
comb Celosia. This was formerly believed to arise from the 
union of several stems ; a manifest error, as an inspection of a 
dissected stem will prove : it is an extremely irregular form- 
ation, something analogous to that which constantly obtains in 
Bauhinia. 
The leaves undergo a thousand metamorphoses, of which I 
shall only select a few remarkable cases. They become suc- 
culent and roll inwards, forming what gardeners call a heart ; 
as in the cabbage and the lettuce. Their parenchyma extends 
more rapidly than the veins and margins; this produces 
puckering, as in curled leaves. If the parenchyma and margin 
are together produced in excess, we then have what gar- 
deners call a curl, as in the plants known by the respective 
names of curled cress, curled savory, curled endive, &c. If 
this tendency to parenchymatous developement proceed much 
further, the surface is not merely puckered, but processes arise 
from it in every direction, and occasionally assume grotesque 
figures, or even the resemblance of other leaves ; the Scotch 
kail of gardeners is an instance of this. The parenchyma is 
formed more slowly than the veins and margins ; this pro- 
duces what are called cut or pinnatifid leaves, as in many 
garden plants, such as the cut-leaved Fagus sylvatica, Alnus 
glutinosa, and others. Occasionally in compound leaves an 
unusual number of leaflets is produced, as seven in some tre- 
foils in room of three ; a doubly pinnate leaf in some roses in 
lieu of a simply pinnate one. In other plants the reverse 
occurs : there is a Dahlia, which constantly produces simple 
leaves in room of compound ones. 
In flowers irregular metamorphoses are extremely common ; 
they consist of a multiplication of the petals, of a transform- 
ation of petals into stamens, and of a change in colour or in 
smell. In roses the multiplication of petals is the nearly 
universal cause of the double state of their flowers : in the 
Rose QEillet, and many Anemones, impletion depends upon a 
