China. Yunnan Province: Dongchuan District, Jiaozishan Mountains, on screes, 26°9'45"N, 102°56'7"E, alt. 3,970–4,000 m, 7 September 2018, Huan-Chong Wang et al. LQ4146 (Holotype: YUKU!; Isotypes: YUKU!)

Hemilophia cardiocarpa is most similar to H. rockii, but clearly differs from the latter by its cauline leaves 5–8 mm long (vs. 3–6 mm long in H. rockii), 2–4 mm (vs. 1–3 mm) wide, pedicel of fruit shorter than or nearly equal to its leaflike bract (vs. significantly longer than leaflike bract) and fruit cordate (vs. spindle or narrowly oblong) in shape.

Perennial herbs, cespitose, rhizomatous. Rhizomes slender, simple or branched, glabrous. Stems simple or few branched, 3–10 cm in length, with appressed, simple and minutely forked, 0.05–0.2 mm long trichomes. Basal leaves rosulate, obovate to oblanceolate, withering and deciduous at anthesis. Cauline leaves alternate; petioles blue-purple, glabrous, 1–2.5 mm long; blade ovate, obovate or oblong, 5–8 mm long, 2–4 mm wide, base cuneate, margin entire, apex usually acute to broadly acute, rarely obtuse; midveins sparsely pubescent adaxially, lateral nerves indistinct. Racemes terminal, usually 5–13-flowered. Pedicels 1–3 mm long, with dense and minute hairs. Sepals oblong or ovate, ascending, equal, caducous in fruit, 1–2 mm long, 0.8–1.25 mm wide, sparsely pubescent abaxially, margins membranous and ciliate, rounded at apex. Petals alternate with sepals, broadly obovate, bluish-white to white, with blue or a few purple veins on the lower half, 4–7 mm long, 2–3.5 mm wide, abruptly narrowed to claw at base, apex shallowly to deeply emarginate, apical notch up to 0.4–0.5 mm in depth. Stamens 6, in 2 whorls, slightly tetradynamous; filaments light yellow to purple, lateral pair slender, 1.2–1.5 mm long, median pairs 1.1–1.5 mm long, strongly dilated and appendaged at base; anthers nearly dark purple, 0.45–0.5 mm long, longitudinally dehiscent. Nectar glands surrounding base of lateral stamens, subtending base of median filaments. Pistil 2-carpelled, ovary sessile, ovate; style cylindric, minutely papillate, nearly equal length to stamens. Pedicel of fruit elongated in fruit stage, 4–6 mm long, shorter than or nearly equal to leaflike bract in length. Fruit cordate in shape, glabrous, dehiscent, 5–5.5 mm long, 3–3.5 mm wide; valves navicular, thinly papery, with a crest of tubercles surrounding margin and extending along midvein; replum slender, 5.3–5.5 mm long; septum absent. Seeds 2 per fruit, usually ovoid, slightly flattened, 3.4–3.8 mm long.

Figure 1. 

Hemilophia cardiocarpa A habit B a portion of stem showing trichomes C cauline leaf D flower (apical view) E petal F median filament G lateral filament H fruit (front view) I fruit (lateral view) J fruit after removal of valves and seeds K seed.

Flowering occurs from May to early September, and fruiting from August to October.

The specific epithet cardiocarpa is derived from the Greek words “kardio” (heart) and “karpos” (fruit), referring to the fruit shape of this new species.

Figure 2. 

Hemilophia cardiocarpa A–C habit D a portion of stem with two cauline leaves E inflorescences in apical view F flower G fruit (front view) H fruit (lateral view).

Chinese Mandarin: xin guo ban ji ji (心果半脊荠).

Hemilophia cardiocarpa appears to be a rare species endemic to the Jiaozishan Mountains, which are located in the northern Yunnan Province of southwest China with a highest elevation of 4344.1m and near to the Jinsha River. The new species grows on basaltic screes or open slopes at elevations ranging from 3900 to 4300 m, its association mainly include Arenaria weissiana Hand-Mazz. (Caryophyllaceae), Draba amplexicaulis Franch. (brassicaceaee), Scrophularia delavayi Franch.(Scrophulariaceae), Meconopsis integrifolia (Maxim.) Franch. (Papaveraceae), Ranunculus hirtellus var. orientalis W. T. Wang (Ranunculaceae) and Veronica szechuanica subsp. sikkimensis (Hook.f.) Hong (Plantaginaceae).

Figure 3. 

Hemilophia cardiocarpa A flower after removal of sepals and petals B lateral filament C median filament D fruit (front view) E fruit after removal of valves and seeds F seed.

(paratypes): China. Yunnan: Dongchuan District, Jiaozishan Mountains, Lanniping, elev. 4300 m, 25 August. 1985, Lan Shunbin 547 (PE); Dongchuan District, Jiaozishan Mountains,Yaojingtan, elev. 4100 m, 25 June. 2020, H. C. Wang et al. DC8448 (YUKU); Dongchuan District, Jiaozishan Mountains, Jinfengkou, elev. 4200 m, 23 May 2021, Ren Zhengtao et al. DC12360 (YUKU).

The presence of cordiform fruits is the most remarkable character to distinguish Hemilophia cardiocarpa from other species of this genus. Morphologically, H. cardiocarpa is most similar to H. rockii (Fig. 4) in having a similar habit and sharing similar indumentum, leaf shape, as well as flower size and arrangement. Nevertheless, it clearly differs from the latter by its cauline leaves usually ovate, rarely obovate or oblong (vs. oblanceolate to narrowly elliptic, or rarely ovate in H. rockii), 5–8 mm (vs. 3–4 (6)) long, 2–4 mm (vs. 1–1.5 (3)) wide, racemes usually 5–13 (vs. 5–6) -flowered, pedicels of fruits shorter than or nearly equal to its leaflike bract (vs. significantly longer than leaflike bract) and fruit cordate (vs. spindle or narrowly oblong) in shape. H. cardiocarpa is also similar to the type species of the genus, H. pulchella Franch., from which it is readily distinguished by the racemes usually 5–13-flowered (vs. 2–3-flowered in H. pulchella), and petals bluish-white to white (vs. pink), 4–7 mm (vs. 2.5–3.5 mm) long, 2–3.5 mm (vs. 1.5–2 mm) wide. Taxa of Hemilophia can be distinguished through the morphological characters presented in the following identification key modified from Al-Shehbaz (2002, 2015).

Figure 4. 

Hemilophia rockii A acauline leaf showing adaxial face B cauline leaf showing abaxial face C a portion of infructescence D fruit.