Visit the back entrance to the Exhibition Garden today! It is a riot of color. Buttercup Bush and Marmalade Bush are blooming at the same time, and the area is brilliant with shades of yellow, orange and gold.
Known also as Downy Senna, and with botanical synonyms of Cassia tomentosa, and Cassia multiglandulosa, Buttercup Bush is widespread across the warmer parts of the world as a cultivated ornamental. Usually a shrub, it can become tree-like (up to 12 feet) with multi-stems giving a striking appearance in the garden. Senna requires lots of sunlight and is tolerant of drought, yet adjusts to moist conditions too. Nor is it particular about soil conditions. It can even be grown as an annual and can be replaced if winter temperatures drop too low for its survival. Its suckering habit, sending up secondary stems from its roots, allows it to become invasive in some climates. In New Zealand it has become naturalized and is considered a weed!
Senna is a woolly shrub with long compound leaves divided into 10 to 14 leaflets. Canary-yellow, five-petaled flowers, drooping in racemes, can completely cover the bush. Inside each bloom are seven fertile stamens, their anthers covered with brown pollen, and three staminodes, smaller sterile stamens. The fruits are long inflated hairy pods that hang with many beans inside. The seeds of various species have played a part in herbal and folk medicines over millennia.
Senna multiglandulosa is native from Mexico to Guatemala, and parts of South America. It spreads easily and is also found on the islands of the Caribbean, in Florida, wherever it finds humid tropical weather. There are almost 300 other species of Senna that are found mainly in tropical areas of the Americas but also in Africa. Our fog and mild climate permit many plants like Senna to thrive at the Garden, giving them extra moisture and moderate temperatures.
IN BLOOM CONTRIBUTORS: Text: Kathy McNeil. Photos: Joanne Taylor, Mona Bourell.