Though garden fashions change, the exuberant success of many familiar plants keeps them popular with amateur gardeners. Some of these plants are so willing to grow that they often appear unbidden in gardens and parks—even through cracks in the pavement. Horticulturists ignore these common plants, relating to them as plants that get in the way of rarer, or more fashionable choices. When used well, however, these common plants are regional garden treasures.
To the casual observer, Chasmanthe floribunda, ornamenting winter gardens with its fine flashes of orange or yellow, appears to be a sort of crocosmia on steroids. Though it is indeed a close relative of crocosmia, a fellow member of the iris family (Iridaceae), close inspection reveals that it is a quite different plant. The flat sprays of two- to five-foot tall leaves appear with fall rains, while crocosmia lies dormant below ground. In mid to late winter, the flower stems emerge. The three-inch long flowers consist of a curved tube ending in six spreading petal lobes, the top one longer than the others. The bottom flowers on a stem open first, resulting in a handsome, arrow-shaped inflorescence. The plants die back in mid-spring, before crocosmia begins to flower.
Source and Uses
In its native area (the southwestern Cape Province of South Africa), Chasmanthe floribunda grows in dampish spots on rocky outcrops. South Africans plant it in large, informal gardens, or, as at Kirstenbosch Botanical Gardens, interplant it with deciduous agapanthus, which produces leaves and flowers in the opposite season. In addition to low maintenance winter color, chasmanthe provides a good cut flower in a season when few are available and attracts hummingbirds to California gardens. It looks good planted in clumps or drifts behind informal plantings that might include large succulents such as century plant (Agave americana).
Care and Propagation
Chasmanthe will survive in Northern California gardens with no care at all, though in drought years, it may need occasional fall and winter watering to assure good growth. It is ideal for unirrigated areas, since it needs no water from mid-spring through fall, but it can tolerate summer water if the soil is well-drained. To keep the garden tidy, cut back the flowering stems after the flowers fade (and before seeds form), and cut off the leaves as they turn brown in late spring. You will need sharp pruning shears to cut the dead leaves almost to ground level, and must not put this task off till fall, or you will be forced to work around the tender new shoots that are growing up through the tough dead leaves. Where winter will bring more than light frosts, dig and store the corms, replanting in early spring when heavy frost danger is past.
Chasmanthe will eventually form a raised mass of corms up to a yard across, and will continue to bloom for years without being divided, but dividing clumps every three to four years will lead to heavier flowering. Dig when dormant and cut apart sections of corms or pry out individual ones, discarding the small offsets and the flattened, dead corms that are stacked under each mature one. Replant right away. While chasmanthe will grow in infertile soil, an addition of compost will give the plants a boost and will improve drainage in heavier soils. If you are using individual corms, plant them in well-drained soil, two to three inches deep and six to ten inches apart. Corms may not flower in the first year after transplanting.
You can also grow chasmanthe from its quarter-inch orange seeds, collected when pods start to split open in late spring or early summer and planted in autumn. Plants grown from seed usually bloom in their third year.
Control and Removal
Should you wish to be rid of chasmanthe that has spread beond its allotted space, dig the corms out at any time, using a digging bar if necessary. Small plants may sprout from missed offsets for a couple of seasons, so it would be advisable not to plant any fall-sprouting member of the iris family (such as watsonia) in the cleared area during that time, or you may confuse it with the chasmanthe that you are eliminating. Chasmanthe floribunda could escape cultivation into adjacent wild areas and has done so in some mediterranean-climate areas, including locations in Australia and in Central California’s coastal counties, but it is not listed as an invasive plant. Care is advised in disposing of extra corms and flower stems with mature seed so that they do not become established in wild areas.
Varieties and Similar Species
For those who prefer pastel colors, there is a form of Chasmanthe floribunda with flowers of a clear, soft yellow. It is often sold as C. floribunda var. duckittii, named after the Duckitt family, on whose South African farm it appeared. Some authorities think the color is determined by a single recessive gene and do not consider it different enough to be a separate variety.
Chasmanthe floribunda and either of two other species live on in old California gardens and may be found at specialty nurseries. Flowers of C. bicolor are deep orange marked with yellow and green, the plants to about four feet tall. Chasmanthe aethiopica grows to only three feet tall and is hardy to zone 8. Its bright orange flowers are all turned to one side of the flower stem; it has a greater tendency toward weediness and has escaped from cultivation in California, so it is best to plant the other species.
Scientific Name: Chasmanthe floribunda
Common Name: chasmanthe, Adam’s rib
Plant Type: bulb (corm)
Bloom time: late autumn to mid-spring
Height: 2-7 ft.
Sun or shade: full sun
Soil needs: fertile or poor, well-drained
Water needs: moderate when growing, none when dormant
Other tolerances: part shade, summer water, cool coastal summers, wind, hot inland summers
Hardiness: Zones 9-11
Chasmanthe (kaz-man’thee) was apparently named for the way the petal tips spread widely, from the Greek chasmamai (yawning or gaping) and anthos (flower). The botanist who created this genus name was probably influenced by the fact that Chasmanthe was formerly included in the genus Antholyza (an-tho-lies’uh). The species remaining in Antholyza have petals spread wide, like the mouth of a raging beast, and their genus name derives from the Greek anthos (flower) and lyssa (rabies). The gape of Chasmanthe petals is a minor echo of that major roar. The specific epithet floribunda (flor-ih-bun’-duh) is from the Latin and means “having many flowers.”
In this issue, we present the first of four selections from Wildly Successful Plants for Northern California Gardens, by Pam Peirce with photographs by David Goldberg. The book will be published by Sasquatch Books in January 2004. It will include fifty of the plants that are among the most common in the gardens, parks, and dooryards of the region, and among the most willing to grow.