Identification:
A shrub, 1 – 4 m tall, with completely smooth bark; young branches are four-angled with four longitudinal grooves. Leaves have an elliptic or lanceolate shape, tapering to a point at both ends, 7 – 11 cm long, 1.5 – 4 cm wide, with 5 – 7 pairs of secondary veins; petioles are 3 – 5 mm long. Inflorescences are cymes, axillary, 2 – 3.5 cm long, the primary axis 8 – 15 mm long, the secondary axis 3 – 5 mm long, with flower stalks 3 – 5 mm long. Flowers are white; the calyx tube is 3 mm long, obconical, terminating in 5 calyx lobes that are 0.5 mm long, rounded at the apex, and with hairs on the margins. The corolla tube is 3 mm long, cylindrical, widening at the throat and with hairs inside, terminating in 5 corolla lobes that are 1.25 mm long, ovate, and rounded at the apex. Stamens lack filaments. Ovary with 2 locules, each containing 2 ovules arranged in a stacked manner; style is 3.5 mm long, with hairs on the upper half, as well as the stigma. Fruit is unknown.
Biology and Ecology:
The plant grows in evergreen tropical rainforests during the rainy season, on mountain slopes, at an altitude of 600 – 700 m.
Distribution:
- Within Vietnam: Recently found in Khánh Hòa province (Nha Trang).
- Worldwide: Unknown.
Value:
Likely a species endemic to Vietnam, a rare and unique gene resource. It has a restricted distribution, the sole representative of the Xantonneopsis genus in Vietnam (Nha Trang).
Conservation Status:
The species has a restricted distribution, and its habitat is threatened by deforestation.
Red List Category:
VU A1a,c (Vulnerable)
Conservation Measures:
The species is included in the Vietnam Red Data Book (1996), assessed as “threatened” (Level T). It is recommended to strictly protect existing individuals in Nha Trang, identify additional distribution sites, and research cultivation methods.