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Understanding Flowering Plants
A Closer Look at Flowers
Flowering plants are more than beautiful; they are miracles of nature.
Nearly all flowering plants produce seed. Some are adapted to reproduce in other—even surprising—ways.
The result is an amazing variety of flowers for home landscapes and flower gardens, from tiny daisies to giant sunflowers.
Some lilies and similar plants produce bulbils at the junctions of their leaves with their stems. When ripe, these fall to the ground and grow into new plants. They may be identical to their parent, or differ in one or more ways because the bulbils formed with the pollen of another plant of the same species.
Other flowers send out specialized shoots called runners. Runners grow out from the plant along the soil’s surface.
Where leaves occur on these runners, they form roots that grow into complete new plants. Some vines also reproduce in this fashion. Each new plant is genetically identical to its parent. This process is called “vegetative reproduction.
Another form of vegetative reproduction occurs with plants that have other types of specialized roots, called stolons, rhizomes and tubers. All these spread underground from below the root crown, or growth point where foliage shoots join the roots.
New plants sprout from these special roots, each identical to its parent plant. Some plants like this are invasive and spread beyond where they were planted. They should be confined to garden planters and containers.
A final category of plants that reproduce by vegetative means are bulbs.
The main difference between bulbs and other growing plants is that they have very specialized roots. You’ll learn about these special flowering plants on the next page [see: Bulb Basics].
Garden-Season Regions
Climate and Hardiness
Weather patterns, long-term climate conditions, latitude, and terrain divide our country into three distinctly different types of growing seasons:
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- Cold-winter regions with hard freezes
- Mild-winter regions with occasional frosts and low temperatures
- Reverse-season regions that rarely experiences temperatures cold enough to kill flowers during winter.
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These three regions roughly correspond to general hardiness classifications applied to most flowering plants:
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- Hardy
- Half-hardy
- Tender or tropical
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Hardy perennials and bubs will grow, reproduce, and live in dormancy year-round in cold-winter regions.
Half-hardy flowering plants survive winters in many cold-winter regions and all of the warmer regions.
Tender and tropical flowering plants are very sensitive to cold temperatures. Many will die with long exposure to any temperature lower than 40°F (4°C).
For convenience, all plants in our flowering plant guides are rated into these general hardiness categories and similar ratings are often listed on plant tags and labels [see: Perennials and Bulbs].
U.S.D.A. Plant Hardiness Zones
To aid gardeners and farmers, the United States Department of Agriculture (U.S.D.A.) also provides guidance for climate and plant hardiness. It divides North America and other areas of the world into 11 plant hardiness zones.
The U.S.D.A. Hardiness Zones are based on long-term extreme minimum annual temperatures [see: Plant Hardiness and Climate].
Many plants are rated as to the zones for which they are best adapted—for example, zones 4–7—and these are usually listed on plant labels and in each of our three guides to flowering plants [see: Perennials and Bulbs].