Sophora tomentosa aka Yellow Necklacepod

Sophora tomentosa is an evergreen shrub or small tree. It belongs to the pea family, Fabaceae. Its native range spans the tropics and subtropics. It grows along tropical coasts across the world. In the wild, it lives on sandy shores and beach grassland. It can form large local stands in these sites. Kew places it in the seasonally dry tropical climate zone.

Useful Tropical Plants lists a height of about 16 feet [5 metres]. Its account also records plants reaching 23 feet [7 metres]. The trunk may reach 1.5 feet [0.45 metres] across. Some trees have no branches on their lowest 10 feet [3 metres]. The plant keeps its leaves year-round. Even small shrubs can bloom and set fruit. Growers use it as an ornamental, including in gardens near the sea.

This species grows best in sun but accepts some shade. It prefers sandy soil with good drainage. It can grow in dry or moist ground. Once established, it can cope with drought. It also tolerates some salt in the soil. A broad soil pH range gives gardeners some choice of site. Root bacteria form nodules and turn airborne nitrogen into usable nutrients. The plant uses some of this nitrogen for its own growth. Nearby plants may also gain some of it.

Fruits take about three to four months to mature after flowering. Sea currents help carry them to new shores. Seeds can float for at least three months without losing germination capacity. Yet tests also found that seawater soaking reduced germination. One Malaysian trial recorded germination over half a month to eleven months. These findings show that seed germination can take a long time.

All parts contain poisonous alkaloids, so this is not a food plant. The root bark and seeds deserve special care. They contain sophorine, another name for cytisine. Useful Tropical Plants reports no known edible uses. People gather the plant for local traditional medicine despite its toxicity. Leaves, roots, and seeds contain alkaloids used in these practices. Such use can cause severe vomiting and purging. It does not show that home use is safe. The seeds also contain a compound with insect-killing properties. People use the hard, heavy wood to make small objects.