Vietnam’s vascular plant flora is exceptionally diverse, with more than 13,500 species recorded, representing an important proportion of global plant diversity and reflecting the country’s wide range of climates, topographies, and biogeographical influences across the Indochina region. This high floristic richness encompasses many endemic and regionally significant taxa, with endemic elements concentrated in isolated habitats such as limestone karsts and montane forests, contributing to its status as a key area for biodiversity conservation in Southeast Asia (Luu-Dam et al., 2023). The genus Capparis L. (Capparaceae) comprises approximately 146 species distributed primarily in tropical and subtropical regions across Africa, Eurasia, Australasia, and the Pacific (POWO, 2025). The Indochinese Peninsula represents a major center of diversification for Capparis, yet the taxonomic treatment of the genus in this region remains challenging. In Vietnam, species numbers reported by different authors have varied considerably over the past century, reflecting both taxonomic complexity and inadequate sampling. In recent years, continued floristic exploration and taxonomic revision have led to the description of several new species (Fici and Sy, 2025), highlighting the country’s significant diversity within Capparaceae. An updated checklist of intrageneric taxa occurring in Vietnam was provided by Fici et al. (2022), including the description of a new species. Currently, the genus Capparis in Vietnam comprises 37 species, 9 subspecies, and 3 varieties, all assigned to Capparis sect. Monostichocalyx, underscoring Vietnam as an important center of species richness and ongoing diversification for the family.

During a botanical survey in Dien Bien Province, northern Vietnam, in 2015, a flowering specimen of Capparis was collected, notable for its distinctive leaf with a long acuminate apex. Comparative analysis with regional Floras and taxonomic monographs (Jacobs, 1965; How, 1979; Pham, 1999; Wu, 1999; Zhang and Tucker, 2008; Maurya et al., 2020; Fici et al., 2022), along with examination of type materials, confirmed the specimen as Capparis urophylla F.Chun. This species has previously been recorded in Hunan, Guangxi, and Yunnan provinces in China (Zhang and Tucker, 2008) and in Xiangkhoang Province in Laos (Fici, 2023), but has not been reported from Vietnam so far.

This paper presents a detailed morphological description of C. urophylla based on Vietnamese specimens, including color photographs and a comparable table to distinguish it from allied Capparis taxa in the region.

Specimens of C. urophylla housed in the A, IBK, L, and SYS herbaria, together with high-resolution digital images from JSTOR Global Plants (https://plants.jstor.org/), were examined. Relevant taxonomic literature (Jacobs, 1965; How, 1979; Pham, 1999; Wu, 1999; Zhang and Tucker, 2008; Maurya et al., 2020; Fici et al., 2022, 2025) was also consulted. A detailed morphological comparison of the Vietnamese specimens with morphologically allied taxa was conducted using published descriptions and type material (Table 1).

Voucher specimens were prepared according to the standard protocol (Bridson and Forman, 1999) and deposited in the herbarium of the Institute of Biology, Hanoi (HN). Field photographs of living plants were taken with a Canon EOS 70D digital camera (Tokyo, Japan), and images of dissected floral and vegetative parts were captured with a Nikon SMZ745 stereo microscope (Tokyo, Japan). Herbarium acronyms follow the Index Herbariorum (http://sweetgum.nybg.org/science/ih/), and morphological terminology in the species description adheres to the standards outlined by Beentje (2010).

Capparis urophylla F. Chun in J. Arnold Arbor. 29: 419, 1948.—TYPE: CHINA. Kwangsi, Hang-On-Yuen, 7 Jun 1936, Z. S. Chung 81701 (holotype SYS; isotypes A 00042261 digital image!, IBK 00016075 digital image!) (Fig. 1).

Shrubs, up to 2.5 m tall. Stems with vertical slender stripes, glabrous. Branchlets green, terete, slender, without stipular spine or with ascending and slightly incurved ca. 1 mm spines; new twigs with extremely thin pale brown hairs, later glabrescent. Stipular spines on stems ca. 2–3 mm long, stout, recurved upwards, apex sharp and yellow when fresh, base inflated and light green when fresh. Leaves simple, alternate; petioles 2–3 mm long; leaf blade ovate, 3.5–4 × 1.7–2.2 cm, membranous when young but herbaceous when mature, apex caudate, falcately curved, 2–2.5 cm long, base cuneate, midvein abaxially raised, adaxially impressed, secondary veins 5–6 pairs, reticulate veins obvious on both surface when young. Inflorescences in superaxillary rows, 1–2-flowered. Flowers bisexual; pedicel 5–6 mm long; sepals 4–4.5 × 2–2.5 mm, outside glabrous, margin and inside hairy; sepals of outer whorl ovate, basally shallowly saccate; sepals of inner whorl elliptic; petals white, oblong, 8–10 × 2–2.5 mm, both surfaces hairy; stamens 9–15; filaments 2.2–2.5 cm; anthers 1–1.2 mm; gynophore 2.3–2.5 cm, glabrous; ovary ovate, 1–1.5 mm, glabrous. Fruits not seen.

Flowering: March to May.

Distribution: China (Hunan, Guangxi, Yunnan), Laos (Xiangkhoang), and Vietnam (Dien Bien Province).

Ecology and habitat: Capparis urophylla was found growing on a rocky slope, at altitudes about 381–747 m asl. in association with Chromolaena odorata (L.) R. M. King & H. Rob., Aglaia poilanei Pellegr., Thysanolaena latifolia (Roxb. ex Hornem.) Honda, Phyllanthus reticulatus Poir.

Uses: Ethnobotanical records from Laos indicate that different parts of Capparis urophylla are used for medicinal purposes: the leaves are applied in the treatment of conjunctivitis, whereas preparations derived from the wood are utilized to alleviate stomach ache (Fici, 2023).

Specimens examined: VIETNAM. Dien Bien Province, Muong Pon commune (Dien Bien District, Muong Pon commune before 1/7/2015), 13 Mar 2015, 21°36′54.2″, 103°01′56.5″E, 381 m asl, T. T. Bach, D. V. Hai, B. H. Quang, S. D. Thuong VK 6260 (HN!). Dien Bien Province, Na Sang commune (Muong Cha District, Sa Long commune before 1/7/2015), 17 Mar 2015, 21°49′52.7″, 103°06′59.8″E, 747 m, T. T. Bach, D. V. Hai, B. H. Quang, S. D. Thuong Thuong 69 (HN!).