Allamanda cathartica (Yellow Allamanda, Golden Trumpet, Buttercup Flower)
That’s how the showy trumpet-shaped flowers of Allamanda cathartica adorn its bush or vine, bountiful in terminal cymes and shining radiantly in rich yellow.
An outstanding ornamental shrub that is ever-blooming, grows easily and requires minimal care.
Like the bougainvilleas that thrive well in a hot and humid tropical environment, Golden Trumpet is seen grown almost everywhere in our beloved country Malaysia, outdoors in gardens, parks, public places, roadsides, highway medians, etc. and blooming spectacularly throughout the year.
For John and I, it is an on-and-off love affair with these golden bells! To grow and marvel its beauty or reject the beast that causes skin rashes and itch with its toxic milky sap…just me affected! Haha…whenever it’s added again to our garden, you’ll know that I had memory loss and forgotten the whole beastly experience! ;)
Plant Profile, Culture and Propagation :
- Botanical Name: Allamanda cathartica (synonyms: Allamanda nobilis, Allamanda grandiflora, Orelia grandiflora)
- Common Name: Yellow Allamanda, Yellow Bell, Golden Trumpet, Buttercup Flower
- Family name: Apocynaceae
- Plant type: Ornamental shrub or quasi-vine, native to Brazil but widely cultivated throughout the tropics.
- Features: Allamanda cathartica, a very popular species with some named cultivars and varieties, of the genus Allamanda, is an evergreen perennial in tropical climate but an annual in frost regions. A vigorous-growing scrambling shrub or woody quasi-vine that can reach 10-20 ft tall with support and spreading 3-6 ft wide, but can be pruned to a more desirable size in cultivation. Foliage is light green or bright to dark green in color, with glossy and leathery leaves (2-6 inches long) that are simple, oblong-lanceolate and pointed at both ends. They grow in whorls of 3-5 or in opposite pairs along the long stems.
Golden Trumpet’s main attraction are the clusters of large funnel-shaped flowers in axillary cymes that are copiously borne at terminal branches. Flowers are colored in varying shades of fabulous yellow, from light to bright yellow or rich to golden yellow. These brilliant flowers with 5 overlapping petals, in single or double-form depending on the varieties, have varying sizes ranging from 2.5-5 inches in diameter. Flowers are short-lived, lasting about two days, but their abundance and year-round spectacular display make it much sought-after.
It bears fruits that appear as prickly capsules which split open when ripe to release winged seeds that can be used for propagation. However, cultivated varieties rarely produce such fruits.
All parts of A. cathartica including the white milky sap that exudes when broken are considered poisonous and highly cathartic, hence the botanical name.
Because of its aggressive growth habit and tendency to coppice vigorously when trimmed, this allamanda species is listed as invasive/weed in some regions, notably in Queensland, Australia and Florida, USA.
- Culture (Care): A. cathartica can be easily grown with minimal maintenance in the tropical and sub-tropical countries.
Light: Full sun to light shade, but grows and flowers best in full sun.
Moisture: Medium water requirements and drought tolerant when established.
Soil: Moist and well-drained humus-enriched sandy soil. Can be adaptable to many soil types but not salt or frost tolerant. A highly alkaline condition can cause it to become chlorotic.
Others: Feed fortnightly with a water soluble fertilizer at half-strength. Prune selectively to shape as a shrubby bush or to maintain a presentable size. A hardy shrub that can take severe pruning, so trim regularly if necessary. If grown as a vine, its branches/stems need staking for support as plant does not bear tendrils. No serious pests or diseases, though occasionally bothered by caterpillars, whiteflies, mealy bugs and spider mites. Learn more on how-to prune.
For sub-tropical regions: Hardiness: USDA Zone 9b-11. A summer annual and winter deciduous in frost regions, so grow in a container and overwinter indoors. Water sparingly during winter and prune in spring before growth begins.
- Propagation: From seeds which are rarely available on cultivated plants. The other alternative and easiest method is from stem cuttings that root easily on soil. Can even be propagated by division of the many sprouts which may emerge at the crown of the main plant.
- Usage: Spectacular flowering shrub for hedges and screens or ornamental specimen in gardens, parks and public places. Suitable too for landscaping along roadsides and highway medians. Ideal to be trained as a vine with support at porches and on trellis, arbors, fences and trees, as well as espaliered on a wall or cascade down a garden wall. It can be grown as a container plant, especially for greenhouses or to overwinter indoors in freezing climate.
As noted at PMC site, in Suriname’s traditional medicine, the roots are used against jaundice, complications with malaria and enlarged spleen, the flowers as a laxative and it has antibiotic action against Staphylococcus besides wound healing activity.
Some of the named varieties of A. cathartica are:
- var. Williamsii – large yellow double flowers, larger leaves (up to 7 inches long)
- var. Stanstill’s Double – yellow double flowers
- var. Hendersonii or Brown Bud – large 5-inch-wide yellow single flowers, brown bud, darker green larger leaves (up to 6 inches long)
- var. Flore Pleno – golden yellow double flowers
- var. Golden Butterfly – large 3-3.5 inch wide bright yellow single flowers, large leaves up to 5-inch long
- var. Schottii, also known as A. schottii/nerifolia (Bush/Shrub Allamanda, Dwarf Golden Trumpet) – smaller 2.5-inch-wide (or less) bright yellow single flowers, throat streaked with orange, buds bronze, smaller/slender leaves about 2-inch-long, more compact growth (about 6 ft tall)
More photos of A. cathartica, grown in our garden and elsewhere:
Allamanda cathartica ‘Golden Butterfly’
Allamanda cathartica ‘Hendersonii’ or ‘Brown Bud’
Allamanda cathartica var. Schottii
Allamanda cathartica var. Schottii