Geography and distribution
Dracaena jayniana is restricted to central and northeastern Thailand. It is found on limestone karsts at 300–500 m above sea level, usually on hilltops rather than the steep cliff sides.
The inaccessible nature of this landscape coupled with its lack of soil and low water availability has helped protect it from agricultural development. It contains many rare and unusual species that are often restricted to karst limestone.
Dracaena jayniana flowers (Photo: Kaweesak Keeratikiat)
Overview: Woody stems up to 8 m tall, branched at the base, with usually 3–5 erect stems in a cluster. Stems bear leaf scars from the base to the apex. Bark pale brown to grey-brown with vertical fissures towards the base, peeling away on each side of fissure. Dark red sap oozes from damaged bark.
Extremely long, woody roots are produced that can reach down to the water table below the arid, rocky limestone habitat.
Leaves: Tough, leathery, pale green to white, in dense clusters at tips of stems. Leaf blades dark green, up to 75 cm long and 1.3 cm wide. All but the youngest leaves are curved near the base.
Flowers: Tepals (undifferentiated petals and sepals) dull golden yellow. Flowers borne on erect to ascending inflorescences with four levels of branching.
Fruits: A berry with up to three seeds, shiny olive-green when immature, probably dull red when mature (known to be red-black when dried), about 1 cm in diameter.
Seedlings: Leaves borne in two opposite rows on the stem (rather than forming a rosette).
Threats and conservation
Dracaena jayniana is considered to be Endangered according to IUCN Red List criteria (preliminary assessment). It is restricted to isolated limestone karst outcrops, resulting in a fragmented distribution. It is slow-growing and has poor fruit-set (relative to other species of Dracaena).
Mature plants are collected from the wild for use in horticulture. However, D. jayniana is less popular than other Dracaena species, and a number of populations are close to temples, which affords them some protection. It is collected by locals who consider it to bring good luck.
In Thailand, many limestone habitats are threatened by extraction for concrete manufacture, especially those closest to cities such as Bangkok.
Dracaena jayniana is cultivated as an ornamental in Thailand.
A tonic drink is made from the dried red sap.
This species at Kew
Pressed and dried specimens of Dracaena jayniana are held in Kew’s Herbarium where they are available to researchers by appointment.