130 PLANT STRUCTURES 
that of a Laurel, and fold it down the mid rib till the 
two edges are in contact. There is-our pea-pod com- 
plete. The young seeds, or ovules, are borne in a 
row along the mid rib, a very usual arrangement. 
Examine next the young fruit of a Columbine 
(Aquilegia). Here there is a group of five separate 
erect carpels, but each is essentially like a pea-pod in 
structure. Compare the fruit of a Saxifrage. This 
clearly consists of two carpels which are grown 
together save at the tips, where the two styles stand 
out like little horns. From this we may go on to 
other pistils in which several carpels are completely 
fused together. Next, the compact body thus formed 
may be sunk down in the expanded top of the stem 
(the receptacle). Or the other parts of the flower— 
sepals, petals, stamens—may in their lower part be 
fused with the walls of the pistil, and may thus appear 
to spring from the top of it. In such cases the struc- 
ture of the flower may easily be wrongly interpreted, 
and reference to a work on systematic botany is 
necessary if pitfalls are to be avoided. It is indeed 
to be noted that in flowers, as in other parts of plants, 
complicated structure or multiplication of parts is 
not necessarily an indication of advanced evolution; 
on the contrary, it is often indicative of a primitive 
condition. Just as in machinery or in organized 
human effort simplification often accompanies im- 
provement, so it is with plant structures. Many of 
the more primitive types of flowers, such as Butter- 
cups or Water Lilies, have a multitude of petals or 
stamens or carpels, while in many of the most special- 
ized, such as Composites or Campanulas, the number 
of parts is much reduced. The primitive wind-pol- 
