Botany For Dummies by Rene Fester Kratz

Author:Rene Fester Kratz
Language: eng
Format: epub
Publisher: Wiley
Published: 2011-06-14T04:00:00+00:00

Asexual reproduction occurs by a variety of methods in plants and can involve different organs:

Stems: Stems may extend from the parent plant, forming new individuals at intervals. Strawberries, such as the plant in Figure 11-1, reproduce asexually by stolons, while potatoes use tubers, daffodils grow from bulbs, and gladioli reproduce by corms. (For the details on these modified stems, see Chapter 4.) In the case of potatoes, the eyes of the potato are actually buds that can grow into new potato stems. The bulbs of daffodil and gladiolus plants get bigger year after year, forming lateral buds that grow into new stems.

Roots: Some plants, such as aspen and poplar trees, send roots out horizontally from the original plant. The horizontal roots grow new stems at intervals, producing large stands of trees that are genetically identical to each other. Other plants, such as dandelion, have a long tap root that can generate new stems if the original stem is damaged.

Leaves: Leaves of the common houseplant Kalanchoë form tiny little plantlets along the edges. These plantlets can drop to the ground, produce roots, and grow into new individuals. Plants called liverworts make tiny little cups called gemmae on the surfaces of their leaf-like bodies. When rain splashes into the cups, clumps of cells break off and scatter, forming new plants wherever they land.

Flowers: Although flowers usually mean sexual reproduction, some plants, such as citrus trees, produce seeds asexually by a process called agamospermys. During agamospermy, a cell from the parent plant develops into a seed containing an embryo that is a genetic copy of the parent.

Fragmentation, the process where a plant part breaks off and develops into a new individual, occurs with stems, roots, and even leaves.

Sexual reproduction

Although asexual reproduction is very common in plants, most plants can also mix it up a little by combining their genetic information with another plant to produce offspring that have unique combinations of genetic information.

Most plants can do asexual reproduction and sexual reproduction, where an egg from one plant combines with sperm from another plant to produce offspring that have new combinations of traits. Tulips, for example, reproduce asexually through tulip bulbs, but also reproduce sexually by making flowers, fruits, and seeds.

The most obvious participants in sexual reproduction are the flowering plants — their showy flowers are basically advertising that they’re looking for a mate — but more subtle plant sex is happening around you all the time. All the cone-bearing plants, such as pine, spruce, and fir, do sexual reproduction, as do flowering trees like maple, oak, and willow. Sex is even going on among the grass and moss under your feet!

Comparing reproductive styles

Both asexual reproduction and sexual reproduction have their advantages:

Asexual reproduction rapidly produces copies of a successful organism.

• Advantage: If the traits of the parent plant are working well in a particular environment, then asexual reproduction will produce more successful organisms without the hassle of finding a mate. In other words, if it ain’t broke, don’t fix it.

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