Dracaena (PROSEA)
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Introduction |
Dracaena L.
- Protologue: Syst. nat., ed. 12, 2: 246; Mant. pl. 1: 63 (1767).
- Family: Dracaenaceae
- Chromosome number: x= 19, 20, 21;D. angustifolia:n= 20
Origin and geographic distribution
Dracaena comprises about 60 species and has a pantropical natural distribution with the exception of South America, where however a few species are locally naturalized. A few species can survive in subtropical climates. The majority of the species occurs in Africa, with a somewhat less important centre of distribution in South-East Asia.
Uses
Records of medicinal applications of Dracaena in the Malesian region are limited. A root decoction is sometimes used to treat gonorrhoea and rheumatism, and the leaves are applied externally against beri-beri.
In Indo-China, Thailand and southern China D. cambodiana Pierre ex Gagnep. and D. cochinchinensis (Lour.) S.C. Chen (synonym: D. loureiri Gagnep.) are used in traditional medicine. A decoction of the woody stem is administered to treat rheumatism, to improve blood circulation, to regulate menstruation and as an antipyretic and antidiaphoretic.
Dragon’s blood is the red resin from the woody stem of some Dracaena species, mainly D. draco (L.) L. from the Canary Islands and D. cinnabari Balf. from Sokotra, but also D. cochinchinensis . It has much been used as a dry powdered herbal remedy in traditional medicine, mainly to stop haemorrhages, but it is no longer important in contemporary medical care.
Leaves of D. angustifolia are also used in South-East Asia as a green dye, and young ones are sometimes cooked to serve as a vegetable. Some Dracaena species are commonly cultivated as foliage ornamentals, often cultivars with variegated patterns on the leaves, and they are also planted in hedges. In Africa Dracaena has a strong reputation as a fetish plant, probably because of its longevity and vitality.
Properties
A number of chalcones, homoisoflavones and aromatic compounds have been isolated from D. cochinchinensis resin and wood. Some of the aromatic compounds showed antifungal activities, a chalcone and a homoisoflavone exibited oestrogenic activity comparable to that of isoflavonoids such as genistein and daidzein, whereas an aqueous extract of D. cochinchinensis wood showed antipyretic activity in animal tests. It also decreased the clotting time of blood in mice, and the recalcification and euglobinlysis time of plasma in rabbits, but had no effect on the prothrombin time. It also possesses antibacterial activity.
Several saponins have been isolated from D. cambodiana , D. draco and the African species D. arborea (Willd.) Link and D. mannii Baker. Some of these exhibited antileishmanial, antimalarial, molluscicidal and cytostatic activities.
Botany
Trees, shrubs or subshrubs, usually entirely glabrous; roots generally orange, sometimes tuberous; stem mostly with conspicuous leaf scars, sometimes with red resin; bark smooth. Leaves usually arranged spirally, sometimes distichously alternate or in pseudowhorls on tops of branches, simple and entire, more or less sheathing at base, sometimes narrowed into a pseudopetiole, mucronate at apex, more or less leathery, closely parallel-veined; stipules absent. Inflorescence a terminal, simple to branched raceme or panicle, congested or not, with or without bracts, with flowers singly, in pairs or few- to many-flowered glomerules. Flowers bisexual, regular, fragrant, nocturnal and flowering for several hours only; pedicel jointed; perianth tubular at base, with 6 lobes recurved at anthesis; stamens 6, inserted near the throat of the perianth tube; ovary superior, 3-celled, style filiform, stigma capitate, usually 3-lobed. Fruit a globose to ellipsoid berry, sometimes 2-3-lobed, usually bright orange when ripe, up to 3-seeded. Seeds lacking a testa but enclosed in an obsolescent layer of sclerotic endocarp cells.
The flowers are pollinated by nocturnal animals such as hawkmoths ( Sphingidae ), but successful self-pollination has also been recorded.
Dracaena has been confused in the literature with quite unrelated genera such as Agave , Cordyline and Yucca (especially with Cordyline ), which means that information on aspects such as phytochemistry of Dracaena should be considered with care. The distinction between Dracaena and Sansevieria is purely traditional and not tenable, and the latter is synonymous with the former.
Ecology
In South-East Asia Dracaena occurs most commonly in shaded localities in lowland rain forest up to 1000 m altitude.
Management Many cultivated Dracaena species are propagated by stem cuttings, which usually root easily. Propagation by tissue culture is often practised for Dracaena cultivated as an ornamental plant.
Genetic resources
The two Dracaena species treated here are locally common and there seems no reason to consider them as threatened, although D. umbratica has a small area of distribution and occurs in a type of habitat under pressure, i.e. lowland rain forest.
Prospects
There is no information on the phytochemistry and pharmacological properties of D. angustifolia and D. umbratica . However, research might be useful considering the interesting pharmacological activities of the related D. cochinchinensis . The botany of Dracaena in South-East Asia is very poorly understood, and a taxonomic revision is badly needed.
Literature
100, 392, 671, 817.
Selection of species
Authors
R.H.M.J. Lemmens
