Modes of Pollination

 

The flower is an organ of reproduction that brings the animal kingdom as a participant in that reproduction.  The showy petals, as well as other parts of the flower that can "stand out" provide an attraction that causes certain animals to visit.  They visit because of the food present, sometimes in gland called nectaries.  The visiting animal often participates, unwittingly, in the pollination process.  The animal benefits from the obtaining of food; the plant benefits because a process was initiated that forms sperm, eventually causing the formation of seeds and fruits.  

Many plants are wind-pollinated.  This would apply to many woody trees from both the Coniferophyta and the Anthophyta.  The list can be long and can often cut across growth types (woody and herbaceous), as well as in different plant families.  The goal here is to share some information that would represent an introduction to a very fascinating kind of biology.

A summary of this process may be found by clicking here.

insectpoll.jpg (35783 bytes)

Typically three kinds of animals visit flowers.  The pictures to the left illustrate these three from top to bottom:  insects, birds, and small mammals such as bats and mice.  The reasons they visit these flowers normally relates to some kind of food interest.  Some flowers have food glands called nectaries.  In most instances, the anatomy of the flower, particular through its color in contrast to its surroundings, give the animal a target to focus on as it approaches and lands.  Some of my attempts to show pollination by insects are found here.

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batpollinator.jpg (39350 bytes)

micepollinator.jpg (27021 bytes)

spectrum.jpg (26107 bytes)

The idea of a "target" involves any kind of flower that presents an anatomy that shows contrast between the rim and center of the flower.  Many flowers show this to us already, but in fact insects utilize a different portion of the visible spectrum, as seen left, above.  What would appear to us as a featureless but pretty yellow flower becomes very different in the eyes of the insect.  The insect sees a dark center and lands there.  Naturally, the center of the flower is where the animal needs to go for food.  The sexual parts of the flower also happen to be there, and you have at least effected a pollination through the unwitting aid of the animal, and this can lead to a fertilization and subsequent seed and fruit formation.  

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insectflowerview1.jpg (25940 bytes)

orchid1.jpg (35160 bytes)

Some members of the orchid family present an anatomy in its floral parts that mimic a female insect.  The male insect then visits the flower and "copulates" with the female.  This movement causes the orchid to get pollinated.  This is a sophisticated way to attract a pollinator, and this orchid obviously depends on the insect for its seed formation.

orchid2.jpg (56668 bytes)

Stapeliaflies.jpg (20595 bytes)

A species of the milkweed family that is succulent, Stapelia, forms a very large flower that puts out the odor or rotten meat. This attracts flies, which become the pollinators.  Here you see some flies near the sexual parts of this flower.  More on this can be found here.

 arum.jpg (25974 bytes)

This dissected flower of a member of the Araceae shows the bottom of a spadix inflorescence.  The pistils are above the stamens.  Below the stamens are hairs.  The insect moves down the spathe toward the bottom where the nectaries are.  The hairs emerge and are stiff, trapping the insect.  Then, as the sexual parts mature, the hairs weaken, and the insect can leave.  It passes over the stamens bringing pollen to the pistils.

mtlaurelpoll.jpg (14789 bytes)

The mountain laurel flower (Kalmia sp. - Ericaceae) has its stamens with the anthers lodged into the petals.  The insect lands, rummaging around the center for nectar, and this loosens the stamens.  They pop loose and 'flog' the insect with the anthers, naturally bearing pollen.

redhotpoker.jpg (25312 bytes)

In this "Red Hot Poker" notice that the open flowers are of a different color than the closed flowers.  This signals to the pollinator the proper color when it comes time to visit the flower.