Harvesting does not usually take place until the trees are at least 10 or 12 years old, unless economic necessity compels the cultivator to harvest them at 4 or 5 years, when the bark will be of inferior quality. They may even be left until they are 20 to 30 years of age, while forest trees may be 40 or 50 years old when they are discovered.
Cassia buds which enter commerce are, as already stated, the dried unripe fruits contained within the calyx cup. They are smooth and greyish-brown or reddish-brown in colour, 6-10 mm long and about 5 mm in diameter at the tip; the calyx is hard and wrinkled. They have a spicy cinnamon-like odour and a warm sweet pungent flavour. They are used in sweet pickles.
Saigon cassia is sometimes considered to be a variety of C. obtusifolium (Roxb.) Nees. It is indigenous to Vietnam. The main commercial source was northern Annam, with Tonkin as a secondary source. It provided the ‘canelle royale’ of the Royal Court of Flue. Saigon cassia, or Annamese cinnamon as it is sometimes called, is highly valued in China, both as a spice and a drug, the bark from the trunks of old wild trees being particularly well regarded. Originally, only wild trees were exploited and were propagated by birds. As the more accessible parts of the forests became depleted, cultivation of the tree increased.
The tree grows on a variety of soils, the best areas being well-drained sides of valleys, where lateritic soils of old volcanic origin run down to alluvial soils in the valley bottoms. The rainfall of these areas is high, reaching 2 500-3000 mm per annum, and this is said to be essential for the production of good-quality bark. Saigon cassia is also grown in the plains, both in plantations and in gardens mixed with other crops, such as bananas, areca nuts and jack-fruit.
Cassia oil of commerce is produced in China. It contains cinnamaldehyde as its major constituent and is used for similar purposes to cinnamon bark oil in perfumery and flavouring (after rectification) but its applications are rather more limited.
The tree can be propagated by cuttings or layers, but these methods are seldom used, although suckers are sometimes transplanted. The tree is usually raised from seed, which should be obtained from selected trees. The fruits are soaked in water, after which the pericarp is rubbed off and the seeds are dried in the shade. They should be planted within a few days, as the seeds quickly lose their viability. The seeds are planted in prepared nurseries, preferably of fine sandy soil, and are shaded and watered. The shade is gradually reduced until the seedlings are about 1 m high at 1 year old, when they are ready for transplanting into their permanent positions. The seedlings should be lifted carefully to avoid damage to the roots and the planting distance varies from 0.9 to 4.5 m, depending upon the soil and other crops. The trees are given an occasional ring-weeding and the lower branches are cut off close to the trunk.
