Flowering plants, or angiosperms, make up about 80 percent of plants on earth. Identifying these plants one at a time has taken botanists hundreds of years—and they are still classifying newly discovered varieties. Most of us are simply interested in the angiosperms in our gardens—we are not botanists, geneticists or biologists. We can use a plant’s characteristics to help us identify mysterious “volunteers” in our yard and plants in the neighborhood we’d like to grow ourselves.
Make a note of how (or if) the plant branches, the shape and arrangement of leaves, and how flowers are arranged on the plant. Flowers may all sit on one stalk, “scape” like day lilies, or be arranged on shrubby branches like a rose. Some flowers, like hostas, gladiolas and day lilies, bloom one at a time in “succession” along scapes. A plant’s habit of growth gives clues to its identity.
Determine what type of angiosperm your plant is. Trees and shrubs are woody plants. Varieties of trees, like magnolia, crab apple and dogwood, as well as their shrubby counterparts, such as forsythia, azalea and hydrangea, brighten spring landscapes. Herbaceous perennials are soft-tissued plants that die down each fall and grow again in the spring; peonies, day lilies, Shasta daisies, hostas and poppies are just a few of the perennials that fill our gardens. Some flowers grow for one season only; annuals like marigolds, snapdragons and zinnias provide color for one summer then go to seed and die off.
Find out when and how the plant flowers. Angiosperms that follow flowering with fruits may belong in the vegetable garden or orchard; squash and plum blossoms, for example, are followed by edible fruit. Roses are followed by rose hips, used by apothecaries and perfumers. Herb blooms are “insignificant”—tiny blossoms that signal harvest time. Most perennials have a specific time of bloom; for example, roses in June, lilies in July, hostas in August and chrysanthemums in September. Annuals have the biggest, flashiest blooms of all—they have only one summer to attract pollinating insects. They will bloom until they can produce seed, often all summer. Perennials and annuals produce seeds in pods or dried petals enclose seeds as they develop.
Note the color and shape of the flowers. Blue is a fairly unusual color in the flower garden; delphinium, lobelia, bellflowers, alliums and herbs provide accents. Yellowish-centered flowers with radiating petals may be sunflowers, asters or daisies. Tulips are shaped like wineglasses and lilies like trumpets. The rose is named for the shade of red found in early varieties.
Look at the way the plant roots itself in the ground. Some plants, like tulips and lilies, grow from bulbs that store a year’s worth of food. Other plants, known as monocots, like tomatoes, corn, gladiolas and zinnias, grow “anchor” roots above ground. Hostas, day lilies and dahlias use a system of fleshy roots, known as tubers, which can be divided to form new plants.
Find out where the flower grows and blooms best. Lilacs, roses and zinnias like full sun. Hydrangea, begonias and impatiens crave shade. Spirea, purple coneflower and Japanese iris will tolerate moist soil, but zinnias thrive in hot, dry soil. These “cultural” requirements are clues to identity. They may also help identify whether a flowering plant will grow well in certain growing zones, which are the divisions based on climate that help classify where and where not plants will grow.