Astragalus liuaiminii belongs to Astragalus sect. Laguropsis (A. subg. Calycocystis) by its acaulescent, densely caespitose, with only white hairs. The calyx expands to become saccate, enveloping the pod.

Figure 1. 

Plants and habitat of Astragalus liuaiminii Z. Z. Yang and Q. R. Liu A Mr. Aimin Liu and the distribution area B habitat C plant D side view of the plant.

China. XinJiang Province. Habahe County. Mt. Talede, 1050 m elev., 9 June 2023, on dry gravelly slopes, A. M. Liu, Z. Z. Yang 2388 (Holotype BNU!)

Figure 2. 

Habit and plant structures of Astragalus liuaiminii Z. Z. Yang & Q. R. Liu A habit B leaf, adaxial view C leaf, abaxial view D mature saccate calyx E half calyx removed exposing immature fruit G–H wings I keel J pistils and stamens.

China. Xinjiang: Habahe County, 1000 m elev., 11 June 2023, A. M. Liu, Z. Z. Yang 2398 (BNU!).

Plants perennial, 3–5 cm tall, acaulescent or nearly so, densely caespitose, covered with white medifixed hairs. Caudex with a pluricipital root crown. Stipules whitish membranous, 3–5 mm long, triangular, adnate to the petiole for ca. 2 mm, densely covered with appressed white hairs. Leaves with single leaflet, 2–3.5 cm long, rhomboid, petiole 0.8–1.5 cm long, very densely covered with appressed white hairs; leaflets obovate to elliptic, subacute at apex, rather densely covered with appressed hairs on both surfaces. Racemes 1–2 flower, 1.2–2.2 cm. Bracts whitish membranous, narrowly triangular, ca. 2 mm long, anther densely covered with short appressed hairs. Pedicels very short, with white hairs. Calyx tubular at anthesis, ca. 9 mm, later enlarged and becoming saccate, spherical-ovoid, 15–17 mm, densely covered with white appressed hairs, and denser towards the margins of teeth; teeth triangular, 2–3 mm long. Petals whitish or pinkish. Standard 25–27 mm long; limb oblong, 6.5–8 mm wide, emarginate, constricted below the middle, gradually narrowing into the claw. Wings 23–24 mm long; limbs narrowly oblong, obtuse, ca. 10–11 × 1.2 mm; claw ca. 13 mm long. Keel ca. 19–20 mm long; limbs narrowly elliptic, with widely-curved lower edge and straight upper edge, pink-purple at apex, ca. 13–14 × 2.2 mm; claw ca. 6 mm long. Ovary sessile, white hairy; style glabrous. Mature legumes not seen.

Figure 3. 

Astragalus liuaiminii sp. nov. A plants B standard C keel D wings E leaf, adaxial view F mature saccate calyx G half calyx removed exposing immature fruit H pistils and stamens.

Flowering in June.

Astragalus liuaiminii is currently known only from Habahe County in northwest Xinjiang Province, China, where it grows at an altitude of 1000–1100 m, on dry gravel slopes.

The species is named in honour of Mr. Aimin Liu, who collected the type specimens.

爱民黄芪 (Ai Min Huang Qi).

Astragalus liuaiminii has a restricted distribution area. It is only known from the upstream region of Habahe County, where there is no natural protection area. The total population size of the species is estimated no more than 100 individuals. According to the IUCN (2022), this new species should be considered as “Critically Endangered” (CR).

The new species is close to A. wenquanensis S. B. Ho, but differs chiefly in leaves having single leaflet (vs. 3–5 leaflets) and inflorescences with 1–2 flowers (vs. 5–7 flowers). It is also similar to A. monophyllus Maxim in leaf shape, but differs in its calyx expanding into a sac-like and totally enveloping the pod (vs. calyx tubular, and ruptured by pod as it matures). Astragalus monophyllus is distributed in the northeastern and southern regions of Xinjiang, and belongs to subg. Cercidothrix, while A. liuaiminii is only found in Habahe County of the Altai Mountains in the northern part of Xinjiang, belonging to subg. Calycocystis. The calyx is an important taxonomic characteristic of the genus Astragalus, these two species have distinctly different calyces representative of different subgenera. The differences between A. liuaiminii, A. wenquanensis and A. monophyllus are summarised in Table 1.