Stellaria procumbens Huan C. Wang & Feng Yang, 2020

Yang, Feng, Liu, Xiao-Lan, Li, Yu-Ran, Tian, Ye & Wang, Huan-Chong, 2020, Stellaria procumbens sp. nov. and S. amplexicaulis comb. & stat. nov. (Caryophyllaceae) from Southwest China, Phytotaxa 435 (2), pp. 192-202 : 195-196

Stellaria procumbens Huan C. Wang & Feng Yang sp. nov. ( Figs. 1–3 ).

Diagnosis:— Stellaria procumbens is most similar to S. longifolia Muhlenberg ex Willdenow (1980: 147) , but clearly differs from the latter by its stems cylindrical, 5–10 cm long, leaves 0.4–1.5 cm long, 0.3–0.7 mm broad, the ratio of length to width of leaves from 13 to 23, cymes usually with 1–2 flowers, and peduncles 0.3–2.5 cm long.

Type:— CHINA. Yunnan Province: Luquan County, Zhuanlong town, Jiaozishan National Nature Reserve, 26°04′58″N, 102°51′04″E, elev. 3380 m, 12 July 2019, H. C. Wang et al. LQ 7217 (holotype YUKU!, isotypes YUKU!).

Additional specimens examined (paratypes): CHINA. Sichuan: Leibo County, elev. 2400 m, 23 June 1959, Z. T. Guan 7620 ( PE) ; Yuexi County, under the fir forests, elev. 3600 m, 30 August 1976, Sichuan Vegetation Team 14096 ( CDBI) ; Emeishan City, Emei Mountains, Jingding , 18 July 1931, F. T. Wang 23373 ( KUN, PE, WUK) ; same locality, 25 July 1931, F. T. Wang 23438 ( KUN, PE) ; same locality, 25 July 1931, F. T. Wang 75095 ( WUK) ; Tianquan County, Erlang Mountains , on gravel slopes, 16 July 1959, Nanshuibeidiao Team 01879 ( PE) ; Tianquan County, Erlang Mountains, Longdangxi , elev. 2100 m, 15 June 1959, Botanical Team of Sichuan Agricultural College 00997 ( CDBI) ; Chongzhou City, Jiguanshan village , elev. 2176 m, 16 June 2016, W. B. Ju et al. AZH01164 ( CDBI) . Yunnan: Lushui County, Pianma town , in the edge of evergreen broad-leaved forest, elev. 2700 m, 17 July 1964, S. G. Wu 8138 ( HITBC, KUN) ; Weixi County, on ravine meadow, elev. 3500 m, April 1935, C. W. Wang 63976 ( PE, NAS, WUK) ; same county, Yezhi town , on grassy slopes, elev. 3600– 3600 m, August 1935, C. W. Wang 68491 ( KUN, PE) ; same county, Kangpu village , in thickets, elev. 3500 m, July 1935, C. W. Wang 64682 ( PE) ; Dali City, the East side of Diancangshan Mountains , the vicinity of Yinglefeng , elev. 3000 m, 8 July 1984, Sino-US Joint Plant Expedition 858 ( KUN) ; Dali City, the East side of Diancangshan Mountains , elev. 3000m, 30 May 1955, C. Y. Wu et al. 1454/2 ( PE) ; Luquan County, Zhuanlong town, Jiaozishan National Nature Reserve , H. C. Wang et al. 0803 ( YUKU) ; H. C. Wang et al. 0497 ( YUKU) ; some locality, near Yixiantian , elev. 3800m, 19 July 2018, H. C. Wang et al. LQ 3196 ( YUKU) .

Description

Perennial herbs, whole plants glabrous. Stems prostrate, slender, ca. 5–10 cm in length, much branched, diffuse or slightly ascending, sometimes radicant. Leaves sessile, linear or acicular, usually slightly, declinate, 4–15 mm long, 0.3–0.7 mm broad, apex acuminate, base slightly narrowed, adaxially dark green, abaxially slightly pale-green. Midveins slightly depressed adaxially. Inflorescences axillary, cymose, 1–2(–5)-flowered; peduncle unequal, slender, glabrous, 0.3–2.5 cm long; bracts narrowly lanceolate, ca. 1–2 mm long, margin white, membranous. Pedicel slender, 1–2.5 cm long; sepals 5, ovate, 2–3 mm long, 0.5–1.5 mm wide, apex slightly acuminate, margin membranous; petals 5, 2.5–3.5 mm long, subequaling or slightly longer than sepals, 2-cleft nearly to base, lobes nearly linear; stamens 10, filaments linear, anthers slightly purple, shorter than petals; ovary ovoid-orbicular; styles 3 to 5. Capsule yellow to brown-black, ovoid-orbicular, 3–4 mm long, slightly longer than the persistent sepals. Seeds numerous, oblate, chestnut to brown, 0.5–0.7 mm long, 0.4–0.5 mm in diam.

Seed micromorphology:—Seeds ovate in shape, usually oblate, 0.5–0.7 mm in length, 0.4–0.6 mm in width. Testa cells gear-shaped, elongated, protruding, margins with 10–17 interdigitated teeth ( Fig. 3 ).

Phenology:— Stellaria procumbens was observed from the field and herbarium to flower and fruit from June to August.

Etymology:—The specific epithet procumbens is a Latin adjective meaning “prostrate” referring to the habit of this new species.

Habitat and distribution:— Stellaria procumbens is found in provinces Sichuan and Yunnan, Southwest China. It usually occurs in humid grassland, on rocky slopes near streams, and in ground cover of the subalpine forests, at elevations of 2100–3800 m.

Figures

FIGURE 1. Stellaria procumbens Huan C. Wang & Feng Yang. A. Habit. B. Flower. C. Fruit. D. Seed (Drawn from the specimen H. C. Wang et al. LQ 7217 (YUKU)).

FIGURE 2. Stellaria procumbens. A. Habit. B. Flower. C. Flower (apical view). D. Flower (showing the sepals). E. Fruit.

FIGURE 3. SEM micrograph of seed morphology of Stellaria procumbens sp. nov. (voucher specimen: H. C. Wang 0497 (YUKU)).