Sunflowers are typical cottage flowers with their great round country faces, which always seem too big for any plant…
Margery Fish, Cottage Garden Flowers
The daisy flower head of many garden favorites — a central disk surrounded by radiating “petals” — is deceptively simple. The small clustered disk flowers are usually fertile, while the petal-like ray flowers are sometimes infertile. The showy rays make the flower head attractive to pollinators. This arrangement and various modifications of it are found through out the Compositae, one of the largest plant families with about 20,000 species.
The Compositae are commonly called the sunflower family, and plants of one of its best-known genera, Helianthus, are known as sunflowers. Several other genera have botanical names that suggest their connection to the Greek word for sun, helios (though in the case of Helenium an early common name was Helen’s flower, derived from the story that the plant resembled one growing where Helen of Troy shed her tears). Whether commonly known as a daisy or a sunflower, the pleasing shape of the composite flower head is an important contributor to the design of the flower garden.
Composites have usually been divided by taxonomists into thirteen tribes, or twelve when two closely related tribes, Helianthus and Helenium, are occasionally combined. It is to these two tribes that the plants discussed here belong. We are interested in plants with decided garden merit, but we will not consider the many double-flowered forms, except to note that the yellow of their pompon-like flower heads makes a most cheerful display. One of these, Rudbeckia laciniata ‘Golden Glow’, six to eight feet tall and with yellow flower-heads resembling chrysanthemums, was ubiquitous in gardens in my grandmother’s time.
If the typical form is that of a daisy or sunflower, the typical color is yellow, although some show shades of bronze and mahogany and a few are purplish pink. Rudbeckia and Echinacea are similar, but rudbeckia flowers are mostly yellow and echinaceas are mostly pink. Rudbeckia, which includes about twenty-five species, is the black-eyed Susan of fields and meadows in the eastern United States. Known commonly as coneflowers, rudbeckias are easy to grow and appreciated for their abundant flowers from midsummer to fall. Some are tall and need staking, but modern cultivars are shorter and more adaptable to garden beds and borders. ‘Goldsturm’ has a good reputation, but ‘Goldquelle’, under four feet, has stronger stems. Perhaps the most useful kinds are to be found in a group of dwarf plants called Rustic Colors.
Echinacea is commonly known as purple coneflower, though the color of the flower is better described as faded rose. Echinacea purpurea (Rudbeckia purpurea), the best-known, Graham Thomas describes as “stately” and “exceptionally handsome.” It grows to three feet or more, with flower heads six inches across, the rays rose-purple and partially pendant from a coppery orange boss or crown. There is a cultivar ‘White Lustre’, whose flower heads, with their lighter central crown and pale cream rays, are appealing to flower arrangers. It is shorter and more compact than other plants of the species and well-behaved in the garden.
The coneflowers are interesting from a botanical point of view. The central disk is made up of many tiny flowers, and this flower-bearing receptacle may be convex, columnar, or conical. The rays usually hang down, emphasizing the importance of the cone, but there are variations. For example, Echinacea tennesseensis has rays with an almost horizontal tilt; they are well-poised and the slightly notched tips and faded rose color give them a special charm.
This plant is on the federal endangered species list, and it does seem a bit more difficult than most composites to grow. I received a plant as a gift and, though I nurtured it with care, it disappeared; a rabbit may have thought it a new delicacy. Since perennial sunflowers are mostly herbaceous, there is hope of life below the sunny, rich, well-drained place where the name tag still expectantly marks the spot.
Coreopsis, in contrast, is easily grown in almost any soil in full sun. The genus includes over a hundred annual and perennial plants, but perhaps the best for gardens is Coreopsis verticillata with its myriad small daisy flower heads and feathery leaves. Of this plant Graham Thomas says ‘if you are looking for a dense, upright bushy plant with hair-fine leaves covered all over for months with bright brassy yellow daisies, this is it.” Now there are cultivars; ‘Golden Shower’ is bright yellow, while ‘Moonbeam’ is creamy yellow. ‘Zagreb’ is smaller than the others, about eighteen inches tall and wide. All the mounds can be pruned to make them more compact. The first crop of flowers can be hedge-clipped and a crop of flowers in the fall will be less profuse but still bountiful. It is an excellent border subject. Grow five to seven plants in a drift and you will have an uninterrupted mass of airy foliage studded with daisies of delicate texture at peak blooming time. This coreopsis is a feature of the big perennial border at Filoli, the famous estate garden in Woodside, California, south of San Francisco.
The mounding habit is unique to Coreopsis verticillata; other species are more open, their foliage more coarse, their stems more wiry and sprawling. The flowers of all coreopsis are yellow; they have a greenish center instead of a cone and they come in single as well as double forms. The cultivars derive from C. grandiflora and C. lanceolata. Sidney Mitchell liked C. grandiflora for California gardens since “it never winterkills in mild climates and often self-sows, its large yellow flower heads bright in the border in summer and fall and good for cutting.” He probably would have liked modern cultivars even better. The best is the dwarf ‘Goldfink’ with dense tufts of spear-shaped leaves and numerous erect stems carrying a succession of yellow daisies with yellow centers and notched rays. “Use clippers to cut [spent] flower stalks at the base,” advise Harper and McGourty in Perennials: How to Select, Grow and Enjoy (HP Books, 1985), “or the plant will be left with unsightly stubble.” Removing dead flowers on any and all perennials, we know, lengthens the season of bloom. Dead-heading is particularly necessary for some kinds of coreopsis, since the greenish center turns dull dirty brown as flowers pass their prime.
Most kinds of helianthus are too rough for tidy gardens but fine for wild areas and sunny banks. Helianthus annuus, with a huge head on a tall stiff stem, is grown for its edible seed; some gardeners used to grow a solid row as a windbreak. H. tuberosus, named and grown for its edible roots, is not particularly ornamental with its stiff stems, small sunflowers, and prickly leaves, but its less desirable features are unobtrusive behind shrubs and it flourishes if the sun shines through a canopy of trees. If you like the taste of the roots, which are especially good in soup, you need not wait until after blooming to harvest them. After a rain is the easiest time. Even if you do an excellent job of digging, there will be enough bits left to increase and provide a crop for next year.
The most distinctive ornamental helianthus is Helianthus angustifolius, narrow-leaved swamp sunflower, found in the wild in low, wet places but nevertheless quite tolerant of drought. Plants grow to seven feet, multiple-branched at the top with many brown-eyed yellow flower heads in fall. The foliage is an asset, narrow-leaved, as the name implies, and plentiful. This plant is especially suitable in a wild garden or on a hillside since it is big and stout, not coarse but strong-looking.
Most helianthus plants have running roots and some are rampant to the point of being invasive. In Your California Garden and Mine, Sidney Mitchell was moved to inquire, “Why aren’t we told more often in nursery catalogs or in garden books of the terrifying spread of which their stoloniferous roots are capable?” Some kinds of helianthus are quite quickly out of bounds, but not all of them are so persistent. Those that are hard to control are fine for naturalizing in rough, untended places.
The perennial species of Helianthus are less well-known than the annuals. Helianthus annuus is an annual, as one might suspect, and some hybrids and some cultivars are ideal for a cutting garden. In a season’s growth the seedlings make wide plants, four to six feet high, and provide quantities of daisies, four or five inches across, enough to pick many stems without seeming to reduce the number on the plant. There are double- as well as single-flowered plants, in several shades of yellow and in bronze and mahogany. The flower heads of ‘Taiyo’ are praised for their formal shape and thick, firm, golden yellow rays with large, dark purple centers.
My favorite helianthus is ‘Italian White’, with near white to creamy primrose ray flowers surrounding a dark disk. The color of the rays is a wonderful contrast to the almost black central knob, with flecks of gold appearing as the disk flowers mature. The foliage is outstanding, the fresh green leaves indented and pointed and of pleasing texture, luxuriant on four-foot stems. The ring of pointed and angled bracts surrounding the flower head is handsome, and the manner in which the flowering stems face in several directions is a decorative feature. Excellent cut flowers, these plants bloom for months, and each two-inch, or larger, flower head lasts for many days. Production of flowers is increased by dead-heading and by cutting for use in arrangements. The main stem is stout, with full but not crowded branching; the plant does not tend to fall over. By September the height will be five feet and the width at least two feet. In autumn it is pleasing to walk down the path and see ahead the pale yellow circles shining softly against dark green foliage or the turning leaves and hips of old-fashioned roses. ‘Italian White’ has a place in my garden near the front of the border.
Heliopsis is equally easy to grow and most of these plants are perennial. They too are tall, three to five feet, but more compact than many kinds of helianthus and generally less invasive. Their culture is the same: full sun in any reasonable soil with occasional summer watering. They usually do not need support and are long-lasting in bloom. There are many cultivars, some single, some double, with colors ranging from orange-yellow to yellow-green. Heliopsis helianthoides ‘Gold Greenheart’ is double, but its green center is visible when the flower head is newly opened. It is one of the best for a mixed border.
Heleniums, or sneezeweeds, are labeled indispensables in the Bressingham catalog, and Graham Thomas says they “provide the backbone, among yellow, orange and brown shades, of the garden from July to September.” The flower head is distinguished by a high cone in the center, sometimes called a hub, and by reflexed, notched rays of yellow, orange, or mahogany. The rays are not stiffly placed; they seem to dance. Helenium hoopesii, from the Rocky Mountains, is not over three feet, with yellow to orange ray flowers in early June. Large, broad, gray-green leaves form a basal rosette. Helenium autumnale is an old-timer, to five feet with branched stems and bright yellow ray flowers. It has produced many cultivars. The one I like best is ‘Bruno’, two feet tall and one of the darkest in flower. H. autumnale ‘Coppelia’ has a distinctive boss. H. autumnale Redgold Hybrids is a group worth seeking out.
These rather large plants of the Helianthus and Helenium tribes have many uses in the garden. The more restrained kinds are valuable in a mixed perennial or shrubbery border. Plants may be used singly as accents or in groups. One or more can be incorporated in a flower bed mostly for cutting. The less refined kinds may be planted in open spaces with perennials of similar character, such as solidago, solidaster, aster, dahlia, salvia, haplopappus, and eriogonum. Don’t be without at least one of these cheerful plants.