Identification:
Medium-sized trees or shrubs, evergreen, 2-16 meters tall, with a diameter of 15-50 cm. Leaves are simple, alternate, and typically clustered at the branch tips. Leaf blades are obovate, 8-30 cm long, 3-14 cm wide, with rounded or blunt apices, a cuneate base, and entire margins. The leaves are fleshy, and both surfaces are covered with long, soft, silvery-white, velvety hairs. The petioles are very short. Secondary leaf veins have 3-4 pairs, and are prominent on both surfaces. Inflorescences are scorpioid cymes, forming panicles at the branch tips, 15-20 cm in diameter. The basic inflorescence has two rows of sessile flowers arranged in a zigzag pattern. The calyx is covered with soft, silvery-white hairs, and is divided into 5 lobes almost to the base. The corolla is funnel-shaped, with a green, hairless tube; lobes are white and nearly circular. There are 5 stamens, not protruding, inserted deep within the corolla tube; the anthers are yellow. The ovary is superior, conical, with 2 locules, each with one ovule; the style is bifid. Fruits are dry, spherical, with persistent calyxes, tightly enclosing the fruit; they are 5-6 mm in diameter, indehiscent, and turn apricot-yellow when ripe; each fruit contains 2 seeds.
Biology and Ecology:
Flowering occurs from March to May, and fruiting from October to December. Reproduction is by seeds and cuttings. This species grows along coastlines and on islands. It is a sun-loving plant, tolerant of drought, strong winds and storms, salt spray, and can survive in coral sand environments.
Distribution:
Within Vietnam: Along the coastlines of Da Nang City and the provinces of Khanh Hoa, Ninh Thuan (Ninh Phuoc: Ca Na), Binh Thuan, Ba Ria – Vung Tau, Kien Giang; on nearshore islands such as Con Co (Quang Tri); and on offshore islands such as Con Dao, Bay Canh (Ba Ria – Vung Tau), and the Truong Sa Archipelago (Truong Sa Lon Island, Nam Yet, Sinh Ton, Son Ca, Song Tu Tay…) in Khanh Hoa province.
Globally: India, Sri Lanka, China (Hainan), Taiwan, Malaysia, Indonesia (Java), the Philippines, and New Guinea.
Value:
Of particular value for its genetic resources, due to its high adaptability to harsh coastal environments. It provides protection against storms and salt water for coastal areas and islands, especially in the Truong Sa Archipelago.
Conservation Status:
Although the species has a wide distribution in coastal regions, the number of individuals is low at each location, habitats are highly fragmented and restricted, and are subject to natural degradation.
Assessment:
VU A1a
Conservation Measures:
The species was listed in the Vietnam Red Data Book (1996) with the assessment “Rare (R)”. Further research and planting are needed in some coastal areas, especially on islands.