Flueggea acicularis (Croizat) Webster in Allertonia 3(4): 304. 1984.

Xu, Songzhi, Gan, Qiliang, Fu, Lianzhong, Jiang, Mingxi & Li, Zhenyu, 2021, Flueggea acicularis (Phyllanthaceae), a narrow endemic species rediscovered in central China, PhytoKeys 172, pp. 57-66 : 57

Flueggea acicularis (Croizat) Webster in Allertonia 3(4): 304. 1984.

Securinega acicularis Croizat in Journ. Arn. Arb. 21(4):491. 1940.

Flueggea leucopyra auct. non Willd.: Hutch. in Sargent, Pl. Wilson. 2:520. 1916.

Types.

China: Hubei (Hupeh) province, Badong (Patung Hsien) county, bush 2-6 feet, cliffs and rocky places, alt. 30-304 m, 24 March 1908, E. H. Wilson 3336 (holotype, A, A00048778; isotypes, A, GH, K, MO, US); l.c.3335 (paratypes, A, US, K); Chongqing municipality (former eastern Sichuan), Wushan county, Wu Gorge (Wu Xia or Wushan Gorge), bush 3-4 feet, March 1908, E. H. Wilson 3344 (paratypes, A, K). (All male specimens, photos, PE!).

Additional specimens.

China: Chongqing municipality, Wuxi county, Jingzhuba, 2009-04-28, Zhen Yu Li & Qi Liang Gan 11751 (female plant, 2 sheets, PE!); 1.c.11755 (female plant, 2 sheets, PE!) (Fig. 1 ); 1.c. 11758 (male plant, 2 sheets, PE!); and 11759 (male plant, 2 sheets, PE!).

Description.

Shrubs, 1-2.5 m high, deciduous. Stems many branched, branches alternate, diverging into an obtuse angle and arranged in two rows, usually with lateral and terminal spines; branchlets of current year’s growth copiously hirtellous, angulate, yellow-brown, gray-brown, glabrate and nitid when old. Leaves alternate, distichous, or 1-3 fascicled on upper part of a branchlet; stipules reddish-brown, lanceolate, 0.7-2 mm long, margins ciliate, apex caudate-acuminate, persistent; petioles 1-5 mm long, copiously hirtellous when young, later glabrate; leaf blade oblong-obovate to obovate, 0.5-2 cm long, 0.4-1.5 cm wide, thickly papery in texture, glabrous except young midrib base, base cuneate, margin entire, flat or narrowly revolute when dry, apex retuse, obtuse or rounded, mucronulate, adaxially green, slightly lustrous, abaxially pale green, midrib extending to apex, lateral veins 4-6 on each side of midrib, alternate, rarely opposite, connected near margin, midrib and lateral veins slightly raised on both surfaces, veinlets reticulate. Plants dioecious. Male inflorescence with solitary staminate flower, axillary; bracts inconspicuous; pedicel 2-5(-7) mm long; sepals 6, ovate-oblong or elliptic, 1.2-1.6 mm long, 0.4-1.3 mm wide, apex rounded, margin erose or fimbriate, membranous, imbricate, slightly recurved, disk glands 6, angled, coherent, 0.4-0.5 mm across; petals absent; stamens 6, free, filaments green-yellow, 1.5-2mm long, anthers yellow, 0.6-1 mm long, theca parallel, longitudinally dehiscent, anther connectives not protruding; pistillode with 3(rarely 2) branches fused to the middle or beyond, the fused portion 0.8-1.5 mm high, the sharply recurved tips 0.4-1mm long. Female inflorescence 1-rarely 2-flowered, arising in leaf axil; bracts inconspicuous. Pistillate flower: sepals 6, ovate-oblong or oblong, 1.5-1.8 mm long, 0.6-0.7 mm wide, apex acute, margin membranous, fimbriate; persistent and reflexed after anthesis; pedicels 5-8 (-10) mm long that elongate to 16 mm in fruit, pendulous; disk angular, 0.8-1.3 mm across; petals absent; ovary globose, 3-locules, each with 2 ovules; styles 3, patent, flattened, each 2-lobed to middle, stigmas rounded at apex, styles and stigmas yellow-green. Capsules oblate, somewhat triangular in cross section, glabrous, ca. 5 mm in diam., green, brown when dry with persistent and nigrescent styles and stigmas, dehiscing through the locules when mature, valves and seeds falling off after dehiscing, columella persistent, 2-2.2 mm long. Seeds ovoid-trigonous, brown, 2.3-2.8 mm long, 1.6-1.7 mm broad at back, ca. 1.5 mm thick, glabrous, with raised pigmented minute rectangular testa cells (Figs 2 , 3 ).

Distribution.

China: Hubei province (Badong county); Chongqing municipality (Wushan county and Wuxi county), alt. (formerly 30-300 m) 175-300 m.

Phenology.

Flowering and fruiting from April to May.

Chinese name.

Mao bai fan shu (hairy flueggea) ( Li 1994), refers to the copiously hirtellous.

Local name.

Yang ci.

Habitat and ecology.

Three Gorges reservoir area is located in a subtropical region. The annual average rainfall is 1000-1400 mm, mostly in July and August. The annual average temperature is 18.4 °C (average temperature in January: 7.1 °C; average temperature in July: 29.3 °C), and the extreme maximum temperature is up to 44 °C. The relative humidity is 60%-80%. The photoperiod in this area is short, affected by the canyon landform and the foggy environment.

The population of Badong. In March, 1908, the type specimen was collected from Badong county, in cliffs and rocky places in the bank of Yangtze river at altitudes from 30 to 300 m, without detailed location. In May, 1997, Mingxi Jiang found ca. 2,000 individuals of F. acicularis in Mazongshan village (31°2'36"N, 110°9'59"E), Badong county. It grows on a slope located in the bank of Yangtze River, at alt. 100-300 m. The main companion species include shrubs: Maytenus variabilis (Hemsl.) C. Y. Cheng, Viburnum utile Hemsl., Vitex regundo var. heterophylla (Franch.) Rehd.; woody liana: Bauhinia brachycarpa Wall. ex Benth.

The population of Wushan county. In 1908, Wilson collected specimens of F. acicularis here, but without detailed location. In August, 1989, Mingxi Jiang et al. found more than 10,000 individuals of F. acicularis in Luyoudong (30°36'24"N, 108°25'30"E), Wushan county. It grows on limestone on the banks of the Yangtze River, at alt. 100-300 m. The main companion species were similar to Mazongshan population. In May, 1990, Zongqiang Xie and Mingxi Jiang et al. found another monodominant community of F. acicularis in Bawuxia in the midstream of Daning river, Wushan county, at alt. 50-250m. The main companion species include shrubs: Euonymus alatus (Thunb.) Sieb., Lespedeza formosa (Vog.) Koehne, Sageretia thea (Osbeck) Johnst., Vitex regundo var. heterophylla (Franch.) Rehd., Zanthoxylum armatum DC. etc; herbs: Arthraxon lanceolatus (Roxb.) Hochst., Phyllanthus urinaria L.; woody liana: Clematis armandii Franch., Millettia reticulata Benth.; herbaceous vines: Cayratia japonica Gagnep. and Dioscorea oppositifolia L. ( Xie and Jiang 1995).

The population of Wuxi county. This population was located in Jingzhuba, off headwaters of the Daning river, Dahe township, Wuxi county (31°21'40"N, 109°24'34"E). It grows in the cracks of limestone on south slopes, at elevations of ca. 250-350 m. The rock surface is mostly exposed and the soil layer is extremely thin. The vegetation consists of open shrubland with heights lower than 5 m and the main companion species include shrubs: Boehmeria clidemioides var. diffusa (Wedd.) Hand.-Mazz., Broussonetia kazincki Siebold, Buddleja davidii Franch., Cotinus coggyria var. pubescens Engl., Debregeasia orientalis C.J. Chen, Flueggea acicularis (Croizat) Webster, Itea illcifolia Oliv., Lespedeza floribunda Bunge and L. formosa (Vog.) Koehne; woody lianas: Ampelopsis aconitifolia Bunge, Holboellia fargesii Reaub., Parthenocissus dalzielii Gagnep.; herbs: Artemisia annua L., A. sylvatica Maxim., Arthraxon lanceolatus (Roxb.) Hochst, Boea hygrometrica (Bunge) R. Br., Bothriospermum zeylanicum (J. Jacq.) Druce, Carex brevicuspis C.B. Clarke, Corydalis ophiocarpa Hook. f. et Thoms., Duchesnea indica (And.) Focke, Eriophorum comosum Nees, Hemistepta lyrata (Bunge) Bunge, Miscanthus sinensis Anderss., Oxalis corniculata L., Setaria viridis (L.) Beauv., Stellaria media (L.) Cyr., Toridis japonica (Houtt.) DC., Youngia heterophylla (Hemsl.) Babc. et Stebb.; pteridophytes: Adianthum capillus - veneris L., Hypodematium crenatum (Forssk.) Kuhn, Pteris vittata L. and Selaginella davidii Franch.; mosses: Conocephalum conicum (L.) Dumort; herbaceous vines: Cayratia japonica var. pseudotrifoliata (W.T. Wang) C.L. Li and Paederia foetida L.. There are about 80 individuals including ca. 20 seedlings, and pistillate plants are in the majority. Since the population is close to the road, the alien weeds Conyza canadensis (L.) Cronq., Bidens pilosa var. radiate Sch.-Bip. and Veronica persica Poir. have invaded the edge of the population.

Provisional IUCN conservation assessment. In 2009, the Three Gorges water conservancy project, the largest in the world, was completed, located in Yichang city, Hubei province. The altitudes of the dam base and dam top are 4 m and 185 m respectively, and therefore we calculated the populations of Badong and Wushan of F. acicularis at alt. lower than 185m have been submerged according to altitude. Based on field investigations and specimens, we are confident that F. acicularis is distributed narrowly, and is endemic to the karst region of the Three Gorges Area in Central China. The provisional conservation status is "Near Threatened" (NT) according to the IUCN red list criteria ( IUCN 2019).

Figures

Figure 1. Flueggea acicularis (Croizat) Webster. (fruiting specimen, Z. Y. Li & Q. L. Gan 11755, PE).

Figure 2. Living plants of Flueggea acicularis (Croizat) Webster A fruiting branches B fruit remnants after dehiscing C branches and spines D staminate flower E, F pistillate flower G capsules (note epicarp dehiscence lines in center fruit).

Figure 3. Herbarium collections of Flueggea acicularis (Croizat) Webster A staminate inflorescence B staminate flower C young leaves and stipules D capsule E seeds F seed (back view) (A, B Z. Y. Li & Q. L. Gan 11758, PE; C, D, F Z. Y. Li & Q. L. Gan 11751, PE).