Astragalus bashanensis Q.L.Gan, X.W.Li & S.Z.Xu, 2023

Xu, Song-Zhi, Gan, Qi-Liang & Li, Xin-Wei, 2023, Astragalus bashanensis (Leguminosae), a new species from Central China, PhytoKeys 219, pp. 49-55 : 49

Astragalus bashanensis Q.L.Gan, X.W.Li & S.Z.Xu sp. nov.

Figs 1 , 2

Diagnosis.

Astragalus bashanensis Q.L.Gan, X.W.Li & S.Z.Xu is similar to Astragalus sinicus L. and A. wulingensis J.X. Li & X.L. Yu, but the new species can be easily distinguished from both by its spreading pubescent indumentum on stems and petioles, petioles longer than the leaf rachis, white bracts, whitish or yellow corolla, longer claw of the keel-petal, persistent pubescence on both sides of pods and smaller seeds.

Type.

China. Hubei Province: Zhuxi County, Quanxi Town, Hongyangou Village , on Hengduan Mountain , alt. 840 m, 32°4'8.5"N, 109°39'26.33"E, June 2022, Q. L. Gan 3295 (holotype: PE!; isotype: HIB!) .

Paratypes.

China. Hubei: Zhuxi County, Jiangjiayan Town, Yanjiajie Village, Piaoshiyan, 3 June 2022, Qi-Liang Gan 3294 (PE!); Quanxi Town, Hongyangou Village, Hengduan Mountain, 7 June 2022, alt. ca. 840 m, Qi-Liang Gan 3295 (PE!); Biaohulinchang, at the foot of Piantou Mountain, alt. 1200 m, Qi-Liang Gan 3287 (PE!); Shennongjia, Dashennongjia, south slopes, alt. 2800 m, flower white, 5 July 1976, Shennongjia Exped. 10718 (PE!, HIB!); Guanmenshan, Shibangou, alt. 2160 m, slopes, 5 August 1976, Shennongjia Exped. 10790 (PE!, HIB!); Guanmenshan, alt. 2150 m, under forests, 5 August 1976, Shennongjia Exped. 10835 (PE!, HIB!); Songluoxiang, Longchahe, Huilongsi, alt. 2000 m, roadside grassland, 2 September 1976, Shennongjia Exped. 22834 (PE!, HIB!).

Description.

Herbs annual or biennial. Primary root slender, 8-12 cm long, yellowish; nodules sparsely on lateral roots. Stem 20-70 cm long, spreading white pubescent; branches from base, prostrate or decumbent, rooting at nodes, internodes 3-8 cm long. Stipules free, triangle-ovate, 3-5 mm long, base 3-4 mm wide, glabrous or with few hairs at apex. Petioles 5-13 cm long, longer than the leaf rachis, spreading-white-pubescent, thickened at base. Leaves odd-pinnate, 7-9-foliolate, rarely even-pinnate 10-foliolate, 5-13.5 cm long, 2.5-6.3 cm wide; rachis sparsely pubescent; leaflets broadly elliptic or broadly obovate, 0.8-3.1 cm long, 0.7-2.4 cm wide, apex emarginate, base rounded or broadly cuneate, margin entire, adaxial surface glabrous, abaxial surface sparsely appressed white-pubescent, the hairs on nerves denser; petiolules less than 1 mm long, densely pubescent. Racemes umbellate, 6-20-flowered, in one, rarely two umbels; peduncles axillary, erect, 10-20 cm long, up to 15-26 cm in fruit, sparsely pubescent; bracts ovate ca. 0.5 mm long, ciliate, white, deciduous after anthesis; pedicels 0.5-1.5 mm long, white-pubescent; flowers spreading or nutant. Calyx tubular, out surface sparsely appressed white-pubescent; tube ca. 3 mm long; lobes 5, subulate, 2.6-3.2 mm long, lower two shorter than the tube, upper three longer than or as long as the tube. Corolla whitish, creamy-yellow, yellowish or deep yellow; standard obovate, 10-13 mm long, 4-5 mm wide, apex emarginate, base broadly cuneate with short claw; wings 8-10 mm long, claw scarcely shorter than the limb, limb oblique-oblong; keel-petal 7-9 mm long, limb crescent-shaped, base auriculate, claw ca. 2/3 of limb length. Stamens (9) + 1, white, ca. as long as the keel-petal. Ovary narrowly linear, both sides white pubescent; style filiform, glabrous. Pod linear, lateral oblate and green when young; mature pod swelling into boat-like, blackish, 2.5-3 cm long, ca. 4 mm wide, both sides persistent white-pubescent, apex with a thicker beak ca. 1 cm long. Seed dark green-brown, lustrous, orbicular-reniform or reniform, 1.5-1.8 mm long.

Phenology.

Flowering from late May to early July; fruiting from mid-June to late August.

Distribution and habitat.

Populations of Astragalus bashanensis are known from Quanxi Town, Zhongfeng Town, Longba Town, Jiangjiayan Town, Piantoushan National Forest Park and Baguashan Provincial Nature Protection Area of Zhuxi County and it is also widely distributed in Shennongjia National Forest Park, western Hubei, Central China. It grows in roadside grassland, on mountain slopes, forest edges or under forest canopy at elevations from 600 to 2160 m.

Etymology.

The specific epithet is derived from the type locality of the new species. Bashan is an abbreviation for Dabashan or Daba Mountains.

Vernacular name.

Ba Shan Huang Qi (Chinese).

Conservation assessment.

During our field investigations in 2021 and 2022, many populations of A. bashanensis have been found in Zhuxi County and Shennongjia Forest Region. The numbers of individuals of each population ranges from dozens to thousands. In addition, it is distributed along roadsides as a weed. We believe that it should have a much wider distribution than what is now known. Due to its wide distribution range and large population size, A. bashanensis is here recommended as Least Concern (LC) ( IUCN 2022).

Results.

Astragalus bashanensis is most similar to A. sinicus and A. wulingensis in having prostrate stems, simple hairs, umbellate racemes, outer surface of calyx sparsely appressed white-pubescent and blackish and boat-like pods, but it can be easily distinguished from both by its spreading-pubescent indumentum on stems and petioles (vs. ascending-pubescent in A. sinicus ; appressed-puberulent in A. wulingensis ), long petioles (5-13 cm long), longer than the leaf rachis (vs. much shorter than the leaf rachis), white bracts (vs. green or flushed purplish), corolla whitish or yellow (vs. purple, pink to white or yellowish flushed purplish at apex), longer claw of the keel-petal (vs. much shorter), both sides of pods persistent pubescent (vs. glabrous or glabrate) and smaller seeds 1.5-1.8 mm long (vs. 2-3 mm long). The diagnostic features between A. bashanensis , A. wulingensis and A. sinicus are summarised in Table 1 .

Figures

Figure 1. Astragalus bashanensis sp. nov. A population B branches C root D, E, F leaves.

Figure 2. Astragalus bashanensis sp. nov. A adventitious roots B petioles C stipules D flowering plant E, F umbellate racemes G bracts H calyx I opened calyx J, K corolla K 1 standard K 2 keel-petal K 3 ovary and stamens K 4 wings L pedicels M young fruits N mature fruits O seeds.