Meiosis and Syngamy Occur in Flower Parts

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A diagram of a flower is depicted below:

The flower is an organ system...a short branch on a plant. As with any shoot it consists of a stem with leaves. The stem here is the pedicel under the flower which terminates in a sometimes-swollen receptacle. The leaves are represented by four separate whorls. The lowest whorl is the calyx made up of sepals; while sometimes green and leaf-like, they can sometimes be almost indistinguishable from petals. Above this is the corolla whorl made up of petals; sometimes showy and fragrant. Above that is the androecium whorl made up of stamens; which produce the pollen grains in the anther at the end of a filament. In the center of the flower is the gynoecium whorl made up of one or more carpels. These may be separate or fused into a single pistil. Inside the ovary of the carpel is a chamber (the locule) where one or more ovules reside. The ovule contains the embryo sac.

The actual form and substance of the flower parts vary tremendously from species to species and assist us in determining the pathways of evolution among the flowering plants. As an example of real flowers, here is the buttercup in side view and face view:

A unique part of sexual reproduction is the movement of the pollen from the anther of the stamen to the stigma of the carpel. This process is called pollination. This process may be achieved by the flower itself (self-pollination; a severe form of inbreeding), by means of an animal vector (a pollinator), or by means of environmental vectors (water, wind). So the form and function of the flower has evolved to facilitate the pollination event. Because of the resulting diversity among flowers, flowers hare critical morphological features used to distinguish and group various species in identification, taxonomy, and phylogeny.

After syngamy, much of the flower goes through senescence processes which might culminate in abscission. However, the ovary at least will remain attached to the plant to develop into a fruit. The ovules inside this ovary mature and develop into seeds. The zygote inside the ovule matures into an embryonic plant. Typically the embryo is sent hormonal signals to halt growth and to become dormant. These developmental processes culminate in a modified senescence process called fruit ripening, and fruit abscission. Plants have also evolved ways to distribute these seeds either by means of actions of the fruit itself, some animal vector (fruit or seed disperser) or some environmental factor (water, wind).

In the next lecture we shall start with an examination of a "typical" cell.

The CBE citation style for this page would be:

Koning, Ross E. 1994. Plant Basics. Plant Physiology Information Website. http://plantphys.info/plant_physiology/plantbasics2.shtml. (4-27-2009).

Contact Information

Email: rkoning@snet.net

This page © Ross E. Koning 1994.