A small amount of a third type, cassia vera, produced mainly in Java, Celebes and other neighbouring islands, is exported mainly from Makassar, the German Federal Republic being the chief importers.

Within each category, there is a further classification according to the thickness of the quills. Ceylon cinnamon quills imported into the United Kingdom are mainly used industrially in the manufacture of a wide variety of processed foods or for the production of cinnamon bark oil or cinnamon oleoresin. A small quantity is either cut up into pieces about 15 cm or ground into a fine powder or mixed with other spices by spice merchants or millers for the retail pharmaceutical and grocery trades.

Kwantung cassia has an oil content of at least 1.7 ml per 100 g, and Kwangsi 3.4 to 4.0 ml per 100 g, according to information provided in 1974 by the Native Product Corporation, Peking (via the British Embassy). This contrasts with Landes (1951), who reported that best quality Kwangsi cassia contained 2 to 2.75 per cent volatile oil and Kwantung 1.0 to 1.2 per cent.

The spices are prepared and supplied to the market in various forms, the most elaborate type of product being the compound cinnamon quills from Sri Lanka.

The National Dahlia Society also works in conjunction with the Royal Horticultural Society towards the better appreciation of the dahlia. The instrument here is the Joint Dahlia Committee, composed of an equal number of members from both societies. This committee is responsible for the classification of the dahlia into its differing forms and sizes, but not for the actual listing of varieties in accordance with this classification which is done by the National Dahlia Society.

Modern varieties, without doubt, are really wonderful, both in formation and in the period and length of blooming. The majority of giant varieties have originated overseas, although we have several raisers of these varieties within the confines of the British Isles, notably that doyen of the dahlia, Mr Harry Stredwick, whose giants are famous the world over.

Certain members of this committee are responsible for the compilation of the National Register of Varieties, a register which is maintained to try to eliminate confusion and duplication of naming wherever possible.

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.

The bark is removed from the standing tree at the time when it lifts easily, starting with the main branches and working down the trunk. A bambdo scaffolding may be erected for the purpose. Horizontal cuts are made about 40 cm apart and vertical cuts some 25-35 cm apart. The rectangles of bark are then removed with the aid of a horn or bamboo spatula. Finally, the tree is felled and the inferior bark removed from the smaller branches. A stump may he left to encourage coppicing.

In comparison to cinnamon bark oil, the production of cassia bark oils is on a relatively small scale with distillation being undertaken in the importing countries. These oils find a limited use in soaps, perfumes, some spice essences and beverages.

Cassia, also known as cassia lignea or Chinese cinnamon, is said to be one of the oldest of spices. It was known in China as long ago as 27 B.C., in Egypt in the seventeenth century B.C., and it is said to have been familiar to all the people of the Mediterranean area at an early date. These statements are open to doubt and there is probably some confusion with some other bark.

They should, however, be planted close enough to encourage the formation of a tall straight trunk with as few branches as possible. The best spacing is about 1 m between plants. The use of Tephrosia candida (Roxb.) DC. as a nurse crop has been recommended in Sumatra. This may be sown six months ahead of the cassia in rows about 1 m apart and the young cassia trees are planted in clearings about 60-70 cm in diameter made in the Tephrosia, which later can be cut back to 15 cm and spread between the rows.

Intercropping in the first year with groundnuts or other crops is sometimes practised, but care is necessary, as damage to the roots of the cassia can result in infection by canker, Phytophthora cinnamomi.

The type of soil has a pronounced effect on the quality of the bark. In Sri Lanka the best cinnamon grows around Negombo in the Colombo District of the Western Province in fine white quartz sand.

The other main cinnamon area is the Galle and Matara Districts of the Southern Province, where the lateritic gravelly soil of the low country produces more rapid growth, but the bark obtained is somewhat thicker and coarser than that of the Negombo District. Rocky and stony ground is unsuitable. Waterlogged and marshy areas should be avoided, as they give an undesirable bitter product which is much less aromatic.

Several cultivars with distinctive local names exist in Sri Lanka. The forms recognized by growers include sweet or honey cinnamon, snake cinnamon, camphor cinnamon, astringent cinnamon, mucilaginous cinnamon, wild cinnamon and bloom cinnamon. Their characteristics are not given, but of these only sweet or honey cinnamon is cultivated extensively.

It is the dominant species of the secondary vegetation of the higher and middle slopes. It also occurs and is sometimes planted in the coconut plantations and is also found in the calcareous coastal flats. Mahe is by far the largest producer, as the very steep rocky terrain of Silhouette makes exploitation difficult.

Cinnamon bark oil is a pale-yellow liquid possessing the delicate aroma of the spice and a sweet and pungent taste. Its major constituent is cinnamaldehyde, but other components present in minor or trace quantities impart the characteristic odour and flavour which distinguishes this oil from other Cinnamomum bark oils. These components include eugenol, eugenol acetate and small amounts of aldehydes, ketones, alcohols, esters and terpenes. Arctander (1960) attributes the powerful characteristic notes of good oils to the presence of methyl-namylketone together with other, aldehydes and ketones. However, detailed studies of the relationship of the oil composition to its organoleptic properties have not been reported in the literature.

The variation in the properties of the spice according to its grading have been described in the `Products and end-uses’ section, and the current standards are given in the ‘Standard specifications’ section.

Cinnamaldehyde was identified as the major constituent of Sri Lankan cinnamon bark oil by Dumas and Peligot (1834, 1835), and more detailed analyses of the oil composition were undertaken later by chemists of the Schimmel Co. (1892c) and by Walbaum and Huthig (1902).

Cinnamon is the dried bark of Cinnamomum verum (syn. C. zeylanicum). It is indigenous in Sri Lanka, which still produces the largest quantity and best quality, mainly in the form of quills. The Seychelles is the second largest producer, the exports being mainly in the form of rough bark. Small exports are made from the Malagasy Republic.

The spice is used in baking and pickling; it has also a limited use in pharmaceutical products and in incense. Like many other spices, cinnamon was regarded as having aphrodisiac properties.

The Chalais, the caste to which the peeling and preparation of cinnamon bark is now restricted in Ceylon, are said to have emigrated from India in the thirteenth century.

Cinnamon was one of the first spices to be sought after by most fifteenth- and sixteenth-century explorations. It was one of the spices which sent Columbus to the west to discover the eastern spice islands. In his diary for 4 November 1492, we read that, following a reconnaissance of the north coast of Cuba, PinzOn, captain of the Pinto, brought Columbus two pieces of bark, claiming that he had found cinnamon. They were probably Capella winterana (L.) Gaertn., which is still known in the West Indies as wild cinnamon. It was the same search for spices which led Vasco da Gama to round the Cape of Good Hope and reach the Malabar coast of India in 1498.

Incidentally, do please note that whatever form of heating is used, the heating elements should be under the bench; this concentrates the heat where it is most required and, in the case of oil stoves, will keep the pathway free from obstructions. If necessary the soil under the benches should be excavated to allow the heaters to be set into position.

On the other hand, the temperature is automatically controlled by a thermostat, so that very little attention is required, and certainly no stoking, which can be a somewhat unpleasant task on a cold night. Of all the various electrical systems available probably the most useful is that based on a water circulatory system, as there is some small reserve of heat should the current fail and, in addition, the drying effect on the air in the greenhouse is not so marked as in the normal radiant type.

As a compromise soil warming cables can be used to heat the tuber and propagating beds. Space heating will still be required as these cables do not cause any appreciable rise in the air temperature, but this need only be sufficient to maintain a minimum of say 4o to 45 F. Even if electrical space heating is used, with the thermostat set about these figures, the cost of heating will not be unduly high. Alternatively, an oil heater may be used to supply the necessary space heating.

If a spare frame is not available, it is possible to use temporary structures made from loose bricks, breeze blocks, and so on, or even to utilise an open part in the garden without protection, say along the outside edge of the dahlia plot, but in such cases it is probably advisable to bury the pots completely, and also to give each plant a light cane.

The National Show, held each year in the two Royal Horticultural Society Halls, is one of the finest in the world at which the amateur predominates in the competitive classes. The trade exhibits also bear favourable comparison with those of other countries.

The usual potting mixtures are quite suitable, preferably containing some nourishment; John Innes No. 2 is particularly good.

Among its activities it makes available all known information on the dahlia, gives advice to members and affiliated societies, maintains a national register of judges and lecturers and co-operates with similar societies in other countries. Covering, as it does, an extremely wide area, there is a Northern Committee, which looks after the main interests of members north of the Trent, organising at least one provincial show, and staffing bureaux at the bigger Northern shows.

Camphor oil is obtained by distilling the wood or leaves of Cinnamomum camphora (L.) Presl, which is a native of China, Japan and Taiwan, the last island producing the greatest amount. C. camphora can be distinguished from the other species of Cinnamomum mentioned above by the leaves being pinninerved, whereas the others have three to five distinct nerves from the base of the leaves proceeding towards the tip; camphor also has stout dormant buds. A large proportion of the world’s camphor is now produced synthetically from pinenc, a turpentine derivative, or from coal tar. Camphor is used in the manufacture of celluloid, in disinfectants and chemical preparations, and has a wide range of medicinal uses. Safrole, produced from the residual oil after camphor extraction, is used in soap and perfume manufacture.

Other species of Cinnamotnum, whose barks are used as spices or in medicine include: C. culilawan (Roxb.) Presl from the Moluccas; C. iners Reinw., which occurs from western India and Tenasserim (Burma) to Malaysia, Indonesia and the Philippines; C. javanicum Bl. in Malaysia and Indonesia; C. part henoxylon (Jack) Nees in Tenasserim and western Malesia; and C. sintoc Bl. in Java. All the binomials and authorities in this section are taken from Kostermans.