Most of these shrubs are evergreen. They come mainly from tropical America. Their height ranges from 6 to 50 feet. Their dark green, shiny leaves are pinnate and they bear terminal clusters of golden-yellow flowers in the summer. Most Cassias are only hardy outdoors in the far South. C. corymbosa, a native from South America, can be cultivated in a cool, sunny greenhouse. C. glauca, a native from tropical Asia, and C. splendida, a native from Brazil, can also be grown in a greenhouse. C. marilandica is a hardy kind of eastern North America that can grow about 3 feet high. Its moderately woody shoots die back in the fall. It produces yellow flowers in late summer. An important product of commerce produced by Cassias is the drug, Senna. This is a laxative and cathartic product of C. acutifolia, a shrub found wild in Nubia and the Sudan. Arabian or Tinnvelly Senna is obtained from C. angustifolia, a plant common in Arabia, southern India and other countries. American Senna leaves are produced by C. marilandica, a United States shrub. Pods and leaves, which are packed separately in bales, enter our drug markets in large amounts.
Pot Cultivation
In the greenhouse, a minimum winter temperature of 50 degrees is required. They should be planted in a soil mixture of equal parts of peat and loam with sand added. In February, the lateral shoots on the main branches should be cut back to within three buds of the base of the past summer's growth. The leading shoots (those found at the ends of the main branches) should be pruned in half in February. Sprits them often until new growth begins, after which they should be repotted into larger pots. When established, a cooler atmosphere is maintained and they should be fully exposed to sunlight to ripen growth for flower production in the summer. When C. marilandica is planted outdoors, it should be set in light, well-drained soil in April; the roots should be protected with a layer of leaves or similar covering in the winter.
Propagation
Shoots can be inserted in pots of sandy peat in March. Place them in a propagating case in a heated greenhouse and when they form roots, pot them in 3-inch pots. Later, they may be transferred to the 5-inch pots in which they will flower the following summer.
Prune the main shoots and side shoots back to three or four buds to ensure bushy plants. These plants need a lot of water during the summer, but little is needed from October to March. The soil must not be dry for too long, though. C. marilandica can be increased through division in the spring as soon as they begin to grow. Seeds may also be sown in March in pots filled with light soil. Place them in a greenhouse that has a 55- to 65-degree temperature.
