Aristolochia vuquangensis (Aristolochia subgenus Siphisia), a new species from Central Vietnam, is described and illustrated here. This species is most similar to A. wardiana and A. forrestiana by sharing an ovate to lanceolate-ovate leaf blade and a cylindric or saccate-shaped limb, but it differs principally from the two species in having a densely brown hirsute outer surface of perianth, an oblong-ovate utricle, 1.1–1.5 cm long, an unequally semicircular 3-lobed limb in pre-anthesis, with a revolute median lobe, larger than two lateral lobes, abaxially concave, and lower one-third of the inner surface of limb densely covered by trichomes. A detailed description, illustrations, information on ecology, conservation status, and comparison with two similar species are also provided.

Argostemma pictum (Rubiaceae), a species occurring in Myanmar, Thailand, Laos and Peninsular Malaysia, is newly reported for the flora of Vietnam; a description, photographs, information on ecology and taxonomic notes are also presented. In order to facilitate identification, we provide an identification key and checklist to the 10 known Argostemma species in Vietnam.

Ophiorrhiza hoanglienensis, a new species from Hoang Lien mountain range, north-western Vietnam, is described and illustrated. The new species is characterized by oblong-lanceolate stipules, equal or subequal paired leaves, congested-cymose inflorescences with 5–10-flowered, distylous flowers, well-developed bracts, lanceolate, 15–20 mm long, unequally 5-lobed calyx with narrowly lanceolate lobes, longest one 3.2–3.5 mm long, shortest one 1.2–2 mm long, exclusively white corolla with 25–28 mm long tube and ovate to broadly triangular lobes, dorsally ribbed without horn. The information on ecology, conservation status, and comparison with similar species is also provided.

Oreocharis phuongii, a new species of Gesneriaceae from central Vietnam, is described and illustrated here. The new species is most similar to O. longifolia by sharing peduncles up to 22 cm long, bracts 2, zygomorphic, yellow flowers with tubular corolla, stamens 4 with two pairs of coherent anthers and capsules up to 6 cm long. It mainly differs from the latter by the combination of some morphological characters of leaves (shape, base, apex and margin), size of calyx lobes, indumentum of corolla tube and inner surface of three lower corolla lobes. Detailed morphological description together with colour illustration, information on phenology, distribution, ecology, preliminarily conservation status of the new species and comparison with its similar species are also presented.

No abstract