Prairie plants — Terminology
FLOWERS Flowers are special to humans. We visit prairies and forests to see them grow wild, we cultivate them in our yards and homes, we give them to others to show we care. Yet why do plants make flowers? Flowers are the reproductive parts of a plant. After the flowers are pollinated, fruits are produced, and inside the fruits are the seeds that ensure future generations. Flowers are arranged together into flower clusters, or inflorescences. There are four basic parts of a flower. The sepals are the outermost part of the flower and are commonly green and leaf-like in texture, although in some species they are colored and petal-like. Collectively, the sepals are called the calyx. The petals are positioned inward from the sepals and are commonly colored and delicate in texture. Petals usually attract pollinators to the flower. Collectively, the petals are called the corolla, and the sepals and petals together are called the perianth. The stamens are inward from the petals and are the "male" reproductive parts of the flower. A stamen usually consists of the anther, which contains the pollen, and a stalk called the filament. Collectively, the stamens are called the androecium. The pistil occupies the central position in a flower and is the "female" reproductive part. It consists of a terminal stigma, which is often sticky, the function of which is to receive the pollen; a style; and at the base, an ovary, which contains one or more ovules. Collectively, all the pistils in one flower are called the gynoecium. A fruit is the ripened ovary of a flower, and a seed is the matured ovule. In many prairie plants, what at first appears to be a "seed" is in fact a whole fruit that contains a single seed; these are usually a fruit type called an achene. Another fruit type is a capsule, which splits open to release the several to many seeds. FLOWER HEADS OF THE SUNFLOWER FAMILY (ASTERACEAE) In the sunflower family (Asteraceae), what looks like a single flower is actually a flower head composed of many small flowers. Each flower has sepals (modified into pappus), petals, stamens, and a pistil. In a typical member of the sunflower family, there are two different types of flowers. The "petals" that are around the edge of the flower head are the ray flowers. In the center of the flower head are many disk flowers. Found at the base of each disk flower is a small structure called the chaff (not always present). The base of the flower head is the receptacle. Underneath the complete flower head are green sepallike structures called phyllaries, which are modified leaves. Some plants, like blazing stars (Liatris species) have only disk flowers. Other plants, such as dandelions (not pictured) have only ray flowers. GLOSSARY achene - a one-seeded fruit that does not split open alkaloid - a chemical compound found in plants that contain nitrogen, often used in medicines, drugs, or as a poison allelopathic - the suppression of growth of one plant species due to the release of chemical substances by another species calcareous fen - a wetland habitat where the water is alkaline capsule - a dry fruit that opens along two or more slits to release the seeds corm - a short, vertical, swollen underground stem of a plant that stores food over the winter and produces new foliage in the spring. degraded prairie - a prairie that has been severely disturbed so that many non-native plants occur and only some plants of the original prairie remain forb - a nongrass-like wildflower found in a prairie glade - an opening in a forest with bedrock on or near the surface and with prairie plants high quality prairie - a prairie that has had little disturbance and inflorescence - a cluster or group of flowers mesic prairie - a prairie where the soil is most for much of the growing season; the most typical kind of prairie found in Illinois prior to European settlement pod - a follicle, a dry fruit that opens by one slit to release the seeds prairie - a habitat where the plants are mostly grasses and forbs rhizome - a horizontal stem that is underground, sometimes thickened and forming an overwintering structure savanna - a habitat with widely spaced trees and a ground cover of grasses and forbs transpiration - the evaporation of water vapor from leaves of plants
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Created November 1997; updated 23 October 2000