Pharmaceutical botany - Lighthouse Survival Blog

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PHARMACEUTICAL BOTANY
I, 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 Leguminosae (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, 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 Campanulacese (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 Primulacese,
Plantaginaceffi and a few other families. In this the carples simply
cover over or roof in a central placental pillar around which the
ovules are scattered.
Pollination.—Pollination is the transfer of pollen from anther to
stigma and the consequent germination thereon. It is a necessary step
to fertilization.
When the pollen is transferred to the stigma of its own flower the
process is called Close or Self Pollination; if to a stigma of another
flower, Cross Pollination. If fertilization follows, these processes
are termed respectively. Close or Self Fertilization and Cross Fertiliza-
tion. Close Fertilization means in time ruination to the race and hap-
pily is prevented in many cases by (a) the stamens and pistils standing
in extraordinary relation to each other, (b) by the anthers and pistils
maturing at different times, (c) by the pollen in many cases germinat-
ing better on the stigma of another flower than its own.
The agents which are responsible for cross pollination are the wind,
insects, water currents, small animals, and birds.
Wind-pollinated flowering plants are called Anemophilous ; their
pollen is dry and powdery, flowers inconspicuous and inodorous, as in
the Pines, Wheat, Walnut, Hop, etc.
Insect-pollinated plants are called Entomophilous. These,
being dependent upon the visits of insects for fertilization, possess bril-