PHARMACEUTICAL BOTANY 
156 
The Placenta . — The placenta is the nutritive tissue connecting 
the ovules with the wall of the ovary. The various types of pla- 
centa arrangement (placentation) are grouped according to their 
relative complexity as follows: (1) Basilar, (2) Sutural, (3) Parietal, 
(4) Central, (5) Free Central. 
Basilar placentation is well illustrated in the Polygonacece (Smart 
Weed, Rhubarb, etc.) in Piper and Juglans. Here, at the apex of the 
axis and in the center of the ovarian base, arises a single ovule from 
a small area of placental tissue. 
Sutural placentation is seen in the Leguminosce (Pea, Bean, etc.). 
Here each carpel has prolonged along its fused edges two cord-like 
placental twigs, from which start the funiculi or ovule stalks. 
Parietal placentation is seen in Gloxinia , Gesneria, Papaver, etc. 
Here we find two or more carpels joined and placental tissue running 
up along edges of the fused carpels bearing the ovules. 
Central or axile placentation is seen in Campanulacece (Lobelia), 
where the two, three, or more carpels have folded inward until they 
meet in the center and in the process have carried the originally 
parietal placenta with them. This then may form a central swelling 
bearing the ovules over the surface. 
Free Central placentation occurs perfectly in the Primulacece, 
Plantaginacece and a few other families. In this the carpels simply 
cover over or roof in a central placental pillar around which the 
ovules are scattered. 
Style. The style is the portion of the carpel which connects the 
stigma with the ovary. It is usually thread-like but may also be con- 
siderably thickened. It frequently divides into branches in its upper 
part. These are called style arms. As many style arms as carpels 
may be present. In the one-carpelled pistil of some Leguminosce , the 
usually bent-up style is the tapered prolongation of a single flower. 
Again, in the apocarpous carpels of many flowers of the Ranuncul- 
acece, each carpel bears a short to long stylar prolongation. When 
the carpels, however, are syncarpous the common styles tend to 
become more or less fused but usually show lobes, clefts or style 
arms at their extremities that indicate the number of carpels in 
each case which form the gynoecium. 
In some plants remarkable variations from the typical stylar 
