December Tree

Overview

Erythrina subumbrans is native to India, Sri Lanka, Burma (Myanmar), Indo-China and Thailand, throughout Malesia (except for New Guinea) to Fiji and Samoa; planted throughout the tropics. Often grown as an ornamental or to provide shade in plantations, the tree has occasionally escaped from cultivation and become naturalized. It is classified as invasive in some Pacific islands. The flowers contain large quantities of nectar and are a major source of food for birds during the dry season. Very young leaves are steamed and eaten in salads in Java. n Thailand, the leaves of this plant have been used as an ingredient in Thai cuisines. The leaves are good and palatable fodder, but if eaten by rabbits can cause sterility and death. The wood is utilized in canoe and raft building. In Papua New Guinea, trees are planted near villages for their showy red flowers, while in certain districts (e.g. Morobe) they are used in ritual ceremonies.

Vernacular Names

Dap-dap (Tagalog-Philippines), Ye-katit (Burmese), Tawng lan (Laos), Thonglang-pa (Thai),  Vông hạt dá (Vietnamese), Dadap dorri (Malay), Dadap (Papua New Guinea).

Agroecology

Occurs in moist valleys, near streams, in open locations and secondary forest at low and medium elevations, where it is usually found at elevations below 1,500 m. It is found in areas where the mean annual rainfall is in the range 500- 2,000 mm and there is a maximum of 4 months with less than 100 mm rainfall. The mean annual temperature is above 22 °C. The trees ar.e fairly tolerant of wind, unless branches have been damaged by borers.

Morphology

• Stem - straight bole reaching 60 cm in diameter, armed with stout prickles.
• Leaves - petiole 8-16 cm long, thickened at the base; stipules orbicular, small, rachis 2-5 cm long, leaflets ovate-triangular-rhomboid, terminal one largest and 8-16 cm × 6-14 cm, base rounded or cordate, apex acuminate, glabrous, petiolule up to 7 mm long; stipels stipitate, cup-like, glandular.
• Flowers - inflorescence racemose, in the upper leaf axils, 5-23 cm long, brownish-tomentose, peduncle 3-15 cm long. Flowers many, arranged in groups of 3, pedicel 2- 3 mm long, in fruit up to 6 mm long, calyx campanulate, 1-1.5 cm long, splitting open up to halfway down, tomentose, yellow-green; standard broadly elliptical, 2.5-4 cm × 2-3 cm, shortly clawed, scarlet, at base inside with numerous white stripes, wings as long as the keel or slightly longer, about 1.5 cm long, pale red with a blackish upper margin; stamens 3-3.5 cm long, monadelphous but vexillary stamen slightly shorter than other ones and only connate for the lower 0.5-1 cm, pinkish red.
• Fruit - a flat, curved pod, 10-15 cm long, on a slender stalk 3-4.5 cm long, lower part seedless and 2-2.5 cm wide, upper part thicker, 1-1.5 cm wide and 1-5-seeded, septate between the seeds, dehiscent.
• Seed - ellipsoid, 7-18 mm × 5-11 mm, smooth, dull black.

Cultivation

• Generative propagation is by seed - fresh seeds, and those harvested within 3-6 months of maturity, can be sown without any special treatment. Germination rates are generally high and are often 100%. Seeds over 6 months old may take between 12-18 months to germinate due to their hard seed coat which becomes tougher with age. Soaking them in hot water, or abrading their seedcoat, can reduce this time considerably. They may be added to water which has just fallen below boiling point and left in the water as it cools for a minimum of one hour, but up to 12 hours for seed 3 years or more old, and then sown in the usual way.
• Vegetative propagation is by cuttings - large cuttings, even if they are 25 cm in diameter, usually root easily

Chemical Constituents

Alkaloids (erysoline, erysopine, and erythratine), saponins, flavonoids (flavanones, isoflavone, pterocarpans [erythrinocarpan]), polyphenols, tannins.

Traditional Medicinal Uses

• In Indonesia the bark is pounded and applied as a poultice against fever. Pounded young leaves are used as a poultice for haemorrhage after giving birth, against menorrhagia and to relieve headache; juice of the leaves is used as an eye-wash and a decoction of the leaves is given for coughs.
• A decoction of the bark is drunk to treat spleen afflictions in the Philippines.
• In Malaysia, the juice of the bark is drunk to relieve cough, and the bark is applied simultaneously as a poultice. An infusion of the bark in vinegar is prescribed for rubbing the body after childbirth, if vomiting occurs.
•  In Thailand, the bark has been used in traditional medicinal remedies to treat microbial infections and nausea.
• Studies have shown antidiabetic, anti-inflammatory, and antimicrobial activities.