Allamanda cathartica is a sturdy evergreen perennial vine here in Honduras. Yellow trumpet and golden trumpet are common names sometimes used, but it is most widely known simply as Allamanda.
It is native to Brazil but has become widely naturalized in tropical areas throughout the world. In Queensland, Australia, it has been declared an invasive species but in most areas of the world it is considered a desirable plant. In most of the USA and Canada, of course, it is treated as an annual or greenhouse plant but can survive short spells as low as 32°F (0°C) and is suitable for growing outdoors only in USDA zones 9-11.
Allamanda is an attractive vine with gorgeous yellow flowers that is ever-blooming in the tropics. The 5 inch (12.5 cm.) flowers are attractive to bees and hummingbirds (which, incidentally, I have been seeing a lot of lately here in La Ceiba, but I am never quick enough with the camera to catch one).
The leaves are glossy and leathery and grow in whorls of four. The leaves and stems exude a white latex sap that is said to irritate the skin. Allamanda prefers full sun. Mine is in a location with morning shade but it seems to be doing fine.
I grew this particular vine from a cutting from a hedge on the grounds of a local hotel. I think the armed guard thought I was a tourist and allowed me to take a piece. The cutting rooted fairly quickly but suffered a miserable young life in its pot due to my neglect. I didn't have a place to plant it in the ground where it would be safe from workers and wheel barrows for almost 2 years. It grew leaves and lost them two or three times before I was able to get it planted. Once in the ground, it forgave me, though, and quickly took off and filled the trellis.
I think this plant is Allamanda cathartica 'Hendersonii,' based on the bronze buds and white speckles inside the flower, shown in this photo. The stems are stiff and break easily when I wait too long to twine them around this metal trellis, another indication that it is the cultivar 'Hendersonii,' and not the species which has thinner more flexible stems.
Allamandas can be propagated from cuttings or seeds, although the flowers on mine drop before producing seeds. This plant can grow 3 to 10 feet (1 to 3 meters) per year up to 25-52 feet (8-16 m.). Hmm, I see a lot of pruning in my future.