Plants can be Monoecious

Some plants have flowers that are not perfect, they do not have both male and female reproductive parts in the same structure. Instead they produce male flowers that have only stamens or female flowers that have only pistils. Monecious plants have both male and female flowers rather that perfect flowers.

Corn (maize) is a good example of a monecious plant species. It has two types of flowers that develop at different parts of the plant. The male flower forms at the top of the plant and is called the tassle. Because of the way grasses such as corn grow, the tassle starts to develop inside the plant and then emerges just a day or so before it is mature and ready to produce and shed pollen. A tassle actually consists of hundreds of male flowers that have stamens but no pistils.

Tassle and maize plant. Image by UNL

Purple Tassle on the left has anters emerged, green tassle does not. Image by Joel Stuthman

The monoecious corn plant has female flowers that develop on the side of the plant and emerge from the leaf node. As these flowers emerge they are called the shoot and they develop into the familiar ear of corn. These flowers only have pistils. The styles of corn are long and grow up from the ovary and out of the sepals (husks). They are called silks because of their length and delicate nature. When pollen from the tassle flower lands on the stigma at the end of the silk, the pollen tube can grow through the silk to the ovary. Obviously corn pollen is capable of growing a long tube!

Ear or shoot flower on corn plant. Image by UNL

Silks being pollinated. Image by Joel Stuthman

Long silks connect to the ovary. Image by Joel Stuthman

Seeds develop from the fertilized ovary. Image by Don Lee



Because corn is monecious and has imperfect flowers what best describes how it will produce seed?

Looks Good! Correct: Because the same plant produces male and female gametes, pollen from the male flower can land on the stigma of the female flower on the same plant (self pollination). It is also possible for the pollen to have come from another plant (cross pollination).

Here's a video of the Flash animation forĀ cross pollination.