Common Name: Black Siris

General Information

Black siris is a medium sized deciduous tree growing up to 22, occasionally to 40 metres tall. The bole can be up to 60cm in diameter[].
Often harvested from the wild for its timber, the tree has also been extensively planted as a shade tree in tea and coffee plantations[]. The shade also provides plantation labourers with a comfortable working environment under hot tropical conditions[].

Known Hazards

The bark is used as a fish poison[].

Botanical References

Range

E. Asia - southern China, Indian subcontinent, Myanmar, Thailand, Laos, Vietnam.

Habitat

Scattered in thin forests from sea level to 1,500 metres[, ]. Open areas, dry deciduous forest, secondary forest, fire damaged forest, hill mixed evergreen forest, hardwood forest, at elevations from 400 - 1,500 metres[].

Properties

Edibility Rating
Other Uses Rating
Habit	Deciduous Tree
Height	22.00 m
Pollinators	Insects
Cultivation Status	Cultivated, Wild

Cultivation Details

Black siris can be grown in the tropics and subtropics at elevations from sea level to 1,500 metres, where it tolerates a wide range of temperatures and rainfall[]. It grows best in areas where the mean annual temperature is in the range 22 - 33°c, though in its natural range the maximum shade temperature varies from 37 - 50°c and the minimum from 0 - 15°c[]. It prefers a mean annual rainfall between 650 - 3,000 mm and normally experiences a 4 - 5 month dry season[]. Seedlings and young trees are susceptible to frost[].
Grows best in fertile soils[]. Requires a well-drained soil and a position in full sun or light shade[]. Young trees require some shade[]. Established trees are drought resistant[]. Prefers a pH in the range 5.5 - 6.5, tolerating 4.5 - 7.5[].
The tree grows sporadically in both dry and moist deciduous forest zones. Under tropical conditions the species is not gregarious. It tolerates hot humid conditions but not waterlogging.
On good sites 5-year-old trees can be 5 metres in height and the trunk 14 cm in diameter[]. A mean annual diameter increment of 1.3 cm has been recorded for this species[].
Trees coppice well, new shoots reaching a height of 3 metres in 2 years after being cut down[].
Plants are susceptible to fire, resistant to weed competition and drought[]. They regenerate naturally in sheltered areas with good soil[].
This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[].

Edible Uses

The bark is used in the manufacture of a fermented sugar cane wine, known as 'basi', and consumed in the Philippines[].

Medicinal

None known

Agroforestry Uses:

Black siris is an excellent companion tree. It fixes atmospheric nitrogen through a symbiotic relationship with bacteria on the root[]. The tree utilizes the subsoil moisture and nutrients not available to plants and protects them from hail and rainstorms[].
It is used in reforestation programmes and is also planted for soil conservation. It produces a well-developed root system that decreases erosion[].
It is planted as a pioneer species in northern Thailand in reforestation projects to restore native woodland - it is planted in degraded woodland and open areas in a mix with various other species that all have the ability to grow fast; produce dense, weed-suppressing crowns; and attract seed-dispersing wildlife, particularly birds and bats[].
The tree has contributed 16 kgs/ha of nitrogen from 655 kgs of dry weight leaf litter in trials and provides organic matter and soil nutrients to the rhizosphere of understory plants[]. Tree canopies decrease soil desiccation and suppress weed growth[].
Its presence in tea monoculture reduces the incidence of tea pests, particularly red spider mites and scarlet mites[].

Other Uses

The tree produces an insoluble gum which is mixed with other gums and used as an extender[].

A brown dye is obtained from the wood[].

The heartwood of mature trees is a beautiful dark brown colour. The wood is hard, close-grained, 20 - 40% stronger than teak[, ]. A premium quality wood, it is suitable for panelling and furniture[, ]. It is also used for carts, wheels, farm implements and construction timbers[].
A valuable fuel wood, dead and defective branches from shade trees are a major source of fuel[].

Propagation

Seed - to break dormancy the seed can be soaked in cool water for 1 hour, in 80 deg C water for two minutes, or in boiling water for 30 seconds[]. Removed from the water, moist seed is stored overnight and then sown the following morning[]. Seedlings emerge within a week. Fresh seed may have a germination rate of 99%[]. Germination of year-old seed decreases to 55-65%[].
Sow 2 - 3 seeds in each container at a depth of 5 - 20 mm and cover with a thin layer of sand[].

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