One of the common names for this plant is popcorn senna, a reference to the shape of a single blossom. Considering the entire plant, it is easy to see how the slender flower clusters inspired other common names including: Christmas candle, candlestick senna and my favorite: seven golden candlesticks. Click to download (800x600) a large version of this image.
Christmas candle is an evergreen shrub or small tree in frostfree areas, but is often grown as an annual in cooler climes. When it doesn't get frozen back, Christmas candle can get up to 30 ft (10 m) tall and, with its candelabra branching, as much as 15 ft (3 m) across. The huge pinnate leaves are up to 30 in (75 cm) long and composed of 7-14 pairs of large, oblong leaflets, each around 3-8 in (8-20 cm) long and 1-4 in (3-10 cm) wide. The cup shaped flowers are bright yellow, and carried in erect terminal clusters arising from leaf axils. The individual flowers are about an inch (2.5 cm) across. The standard is the longest petal and the other petals are similar to each other. The sepals that protect the flowers before they open are waxy and smooth to the touch. The candle-like flower clusters include open flowers at the bottom and unopened flowers with their waxy coverings at the top. The clusters stand 6-24 in (15-60 cm) tall. The fruit is a straight or slightly curved, winged pod around 4-8 in (11-19 cm) long. Late in the season, the inflorescence will have dry, brown pods at the bottom; green, still ripening pods above that; open flowers above that; and waxy sepal-covered flowers at the top.
Location Senna (or Cassia) alata hails from the Tropics, including Africa, Southeast Asia, the Pacific Islands, and even tropical America. Such a widespread natural distribution for a single species is very uncommon.
Culture Light: No surprise here - Christmas candle performs best in full sun. Moisture: Normal garden soils and moisture suit this tropical shrub quite well. Mature plants are drought resistant. Hardiness: USDA Zones 10-11. Christmas candle is a tropical shrub that dies as soon as temperatures get near freezing. But in Zones 7,8 and 9 you can grow it as an annual. Just start from seed along with your peppers and tomatoes each spring. It will still get 6-10 ft (2-3 m) tall and begin blooming in October. Propagation: Christmas candle is easy to start from seed, and you can expect volunteer seedlings to emerge under last year's plants in late spring when soil temperatures warm. However, we recommend starting seeds indoors several weeks before the last frost to give the plants a head start on the season.
This shrub-sized patch of Christmas candle is growing in Zone 8 where it dies back in winter and renews itself each spring.
If you do not live in a frostfree climate, try growing a few Christmas candles along with castor beans (Ricinus cummunis), banana plants (Musa X paradisiaca), and yuca (Manihot esculenta) to have a little bit of tropical lushness in your temperate zone garden. All these will die to the ground in winter, of course, but they grow so fast (banana returning from its roots, yuca from a cutting, and the others from seed) you will have a tall, robust tropical looking garden by the end of a Zone 7, 8 or 9 summer. In frostfree areas, use Christmas candle in a shrub border or as a specimen plant. The bright yellow flowers attract insects, including butterflies and bees. In my garden, there are almost always some fire ants on the flowers (and even I don't consider that a plus). Christmas candle has a long blooming season, from autumn throughout the winter, or at least until the first frost.
Christmas candle is one source of chrysophanic acid, which is used in medicines that treat certain skin diseases, including ringworm. The compound is believed to have antiviral properties as well.
Features Senna and Cassia are two genera that are sometimes combined, sometimes not, and contain species that can't seem to decide which genus they should be in. (Or is the botanists who can't decide?) Recent authors list about 260 species of Senna and 535 species of Cassia. Most are tropical, but both genera include a few temperate species.