Rubiaceae

Ridsdalea sp. nov.?

Ridsdalea vietnamensis (Tirveng.) J.T.Pereira (=Rothmannia vietnamensis Tirveng.) aff.

Bac Kan Province, Ba Be District, central part of Ba Be National Park. Dray evergreen broad-leaved old secondary forest with domination of Burretiodendron hsienmu, Streblus asper and Arenga pinnata on crystalline highly eroded rocky limestone along Ba Be River at elevation about 250 m a.s.l. Tree 15-20 m tall on rocky slope in humid valley between limestone hills. Flowers white, inside tube with pale purple marks. Fruits broadly ellipsoid to almost globular, dark green, 4–5 cm in diameter, 4.5–8 cm long, inside with black jelly and (15)20–55(65) hard stony white (but with dark brown cover) triangular flattened seeds 1.5–1.8 mm broad. Occasional.

17 November 2022, Nguyen Huu Cuong, Cao Xuan Hai, L. Averyanov, T. Maisak, AL 1680.