CHAP. II. 
FRUIT. 
225 
hazel nut ; or separates regularly round its axis, either wholly 
or partially, into several pieces : the separation is called dehis- 
cence^ and such pieces valves ; and the axis from which the 
valves separate, in those cases where there is a distinct axis, is 
called the columella. 
When the dehiscence takes place through the dissepiments, 
it is said to be septicidal ; when through the back of the cells, 
it is called loculicidal ; if along the inner edge of a simple 
fruit it is called sutural; if the dissepiments are separated 
from the valves, the dehiscence is named septifragal. 
In septicidal dehiscence the dissepiments 169 
divide into two plates and form the sides of 
each valve, as in Rhododendron, Menziesia, / \ 
&c. Formerly botanists said that in this 1 — « 
sort of dehiscence the valves were alternate 
with the dissepiments, or that the valves had 
their margins turned inwards. This may 
be understood from Jig. 169., which represents the relative 
position of parts in a transverse section of a fruit with septi- 
cidal dehiscence ; v being the valves, d the dissepiments, and 
a the axis. 
In loculicidal dehiscence the dissepiments 
form the middle of each valve, as in the lilac, 
or in the diagram 170., where the letters 
have the same value as above. In this it 
was formerly said that the dissepiments were 
opposite the valves. 
In septifragal dehiscence the dissepiments 
adhere to the axis and separate from the 
valves, as in Convolvulus; or in the dia- 
gram 171., lettered as before. 
In sutural dehiscence there are no disse- 
piments, the fruit being composed of only 
one carpel, as the Pea. 
Besides these regular forms of valvular dehiscence, there is 
a mode which obtains in a very few plants, called circumscis- 
sile. This occurs by a transverse circular separation, as in 
Anagallis ; in Jeffersonia it only takes place half round the 
fruit. 
Q 
