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Plant Highlight: Coreopsis gigantea (Leptosyne gigantea)
By Brian Kemble
Family placement and area of occurrence
The Daisy Family (Asteraceae) is a very large one with a worldwide distribution, containing over 32,000 described species in over 1,900 genera. One genus found in North and South America is Coreopsis, with about 75 species of annuals and perennials. Some of these are common wildflowers, such as Coreopsis lanceolata (known as lanceleaf tickseed), Coreopsis grandiflora (large-flowered tickseed) and Coreopsis tinctora (plains coreopsis), notable for their vivid yellow or red-and-yellow flowers. The largest species of all is Coreopsis gigantea, a California native with succulent stems that may reach a height of as much as 10 feet (3 m). It is a perennial and is found in coastal central and southern California, as well as in northern Baja California.
About the plant
Coreopsis gigantea comes from a region with winter rainfall and dry summers, so it has a resting period in the summer months, when its leaves dry up. A plant in the dry season may appear to be dead, with its stout stems (up to 4 inches in diameter, or 10 cm) topped with a mop of brown dried leaves. However, the arrival of the rains in the fall brings forth a new crop of bright green leaves, followed in late winter to spring by its bright yellow flowers.
Plants of Coreopsis gigantea are often single-stemmed, but they may have one or several side-branches. Because the leaves (whether green ones in growth mode, or brown ones in dormant mode) are clustered at the tops of the stems, the pale succulent stems are on full display, and these are smooth except for the persistent leaf-attachment scars, which have an ornamental appeal much as they do on a palm trunk. The leaves are up to about a foot long (30 cm), and they arch outward. They are much-dissected into narrow fleshy segments, and this gives them a fine-textured appearance like carrot tops.
About the flowers
The branching inflorescences emerge in late winter to spring, bearing multiple showy yellow flower heads. The inflorescences may rise above the leaves, but sometimes they extend out to the side or even droop downward. It shoud be noted that (as with other members of the Asteraceae) what is commonly referred to as a “flower” in everyday conversation is actually a cluster of tiny flowers, ringed by ray flowers that have one side greatly elongated. The ring gives the cluster the appearance of a single flower, when it is actually many.
Plants in cultivation
Coreopsis gigantea is not difficult to grow, although good drainage is important and excessive moisture in summer should be avoided. It likes a sunny position and is content with no supplemental water at all if grown in a winter-rainfall climate. It is adapted to coastal conditions, and it does not have very much cold tolerance, so growing it in inland locations with colder winters can run the risk of freeze damage. However, brief dips down to 25° F (-4° C) are not too much for it.
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