Lagerstroemia yangchunensis B. H. Wu & G. D. Chen, 2025

Wu, Bao-Huan, Liu, Xiu-Ting, Bao, Zi-Yu, Ma, Xiao-Yan, Chen, Ying, Chen, Guo-Di, Hu, Xing, Liu, Guo-Feng & Dai, Se-Ping, 2025, Lagerstroemia yangchunensis (Lythraceae), a new species from Guangdong, China, PhytoKeys 255, pp. 35-40 : 35-40

Lagerstroemia yangchunensis B. H. Wu & G. D. Chen sp. nov.

Fig. 1

Type.

China • Guangdong: Yangchun City, Chunwan Town, Xinglong Country , in forest, on sunny slope. 22.3327°N, 112.0097°E, 205 m a. s. l., 28 Jun 2024 (fl), B. H. Wu Lg 2024142 (holotype: IBSC!; isotypes: CANT!, CNBG!, SYS!) .

Diagnosis.

Lagerstroemia yangchunensis is morphologically similar to L. duperreana , but distinguished by its coarse bark with vertical fissures, calyx lobes glabrous inside, and flowers with shorter pseudopedicels and petals with longer claws.

Description.

Trees to 15 m tall. Bark greyish brown, thick and coarse, vertically fissured; branchlets glabrous, terete. Leaves alternate, rarely subopposite; petiole 4–8 mm long, glabrous; leaf blade papery, margin entire, elliptic-oblong, oblong, rarely obovate, 10–14 × 3.5–5 cm, base cuneate to acute, apex acute, acuminate, rarely obtuse, adaxial surface green, glabrous, abaxial surface pale green, slightly pubescent along midvein, lateral veins brochidodromous, 10–15 on each side of midvein. Inflorescences paniculate, terminal or axillary; panicles 9–22 cm long, puberulous with whitish brown hairs. Pedicels 2–5 mm long, densely whitish tomentose; flower buds densely whitish tomentose, obovoid (excluding pseudopedicels), 7–9 mm long, pseudopedicel 2–3 mm long; flowering calyx tubes (excluding pseudopedicels) cup-shaped, 6–8 mm long, outside densely whitish tomentose, distinctly 12 - ridged, inside glabrous, lobes 6, triangular to slightly acuminate, 2.5–4.3 × 2–3.5 mm, reflexed, epicalyx minute, pseudopedicel 2.5–5 mm long; petals 6, crumpled, ovate to broadly ovate, 15–20 mm long including 9–10 mm long claw; stamens 30–40, dimorphic, with 6 stamens longer (21–24 mm long), thicker and the lower half reddish purple in color, the remaining stamens shorter (10–13 mm long), thinner and white in color, filaments glabrous; ovary glabrous, styles 22–30 mm long, glabrous, stigmas small. Capsules oblong, smooth, 16–19 mm long, ca. 10 mm in diameter, loculicidally dehiscent, 5 - valved. Seeds 7–10 mm long including wing.

Phenology.

Flowering from June to July, fruiting after July.

Distribution and habitat.

Lagerstroemia yangchunensis is hitherto known from its type locality, Chunwan Town, Yangchun City of Guangdong; only 4 individuals were found in the population. It grows in forest on sunny slopes at ca. 200 m elevation.

Etymology.

The species epithet “ yangchunensis ” refers to Yangchun County, the locality where this species was discovered.

Vernacular name.

The proposed Chinese name for Lagerstroemia yangchunensis is 阳春紫薇 (yáng chūn zǐ wēi).

Discussion.

Lagerstroemia yangchunensis is morphologically similar to L. duperreana ; however, it can be easily distinguished from the latter species by several characteristics, such as bark coarse and vertically fissured, calyx lobes glabrous inside and flowers with shorter pseudopedicels and petals with longer claws. A detailed comparison is summarized in Table 1 .

Having large inflorescences with flowers boasting vibrant purple colors, Lagerstroemia yangchunensis is a potential ornamental species for urban landscaping or Lagerstroemia breeding. However, its restricted distribution to the edge of a managed woodland in Chunwan Town poses significant threats to its survival. The small and isolated population, coupled with interference from human activities in its habitat, makes this species highly vulnerable to extinction. To ensure the species’ long-term viability and promote its sustainable development, urgent conservation measures, such as habitat protection, seed banking, ex situ cultivation, and public awareness campaigns, are necessary.

Additional specimen examined.

China • Guangdong Province: Yangchun City, Chunwan Town , 22.3327°N, 112.0097°E, 205 m a. s. l., 28 Jun 2024 (fl), B. H. Wu Lg 2024141; ibid., 28 June 2023, B. H. Wu Lg 2024143, Lg 2024144 .

Figures

Figure 1. Lagerstroemia yangchunensis A canopy view during flowering period B stems C flowering branchlet of the inflorescence D flowering branch E fruiting branch F part of the abaxial leaf surface G floral axes H leaves I flower buds J flower K gynoecium L petals M longer stamens N shorter stamens O capsules P seeds. Photographed by Guo-Di Chen and Bao-Huan Wu.