Elatostema × hybrida Y. H. Tseng & J. M. Hu

Tseng, Yu-Hsin & Hu, Jer-Ming, 2014, A new hybrid from Taiwan, Elatostema × hybrida (Urticaceae), is the first confirmed natural hybrid for Urticaceae, Phytotaxa 161 (1), pp. 43-60 : 52-53

Elatostema × hybrida Y. H. Tseng & J. M. Hu , hyb. nov. ( Fig. 1 & Fig. 2 )

Natural hybrid between E. lineolatum var. majus and E. platyphylloides . It differs from the parental species by the shallowly cordate leaf base or the distal half of the leaf base semi-sagitate with an auriculate limb not crossing the petiole to the opposite; acroscopic leaf margin with 7–13 teeth, basiscopic leaf margin 11–17.

TYPE: — TAIWAN. New Taipei City: Pingxi District, Sandiaoling, along a trail to Sandiaoling Water Trail , 25°03’38.92”N, 121°49’49.41”E, 180 m, 11 July 2009, Y. H. Tseng 1117 (holotype TAI! , isotype TAIF! ).

Perennial monoecious herbs. Stems somewhat woody towards the base, erect or ascending, branched, up to 1 m high, ca. 0.8 cm thick, grey-brown, densely hispid, hairs 0.35–0.85 mm long, linear. Stipules 2, opposite, caducous, 9–13 mm long, 1–2 mm wide, lanceolate, greenish, ciliate. Leaves alternate, sessile or subsessile; lamina 7–18 cm long, 2.5–6 cm wide, asymmetrically oblong, chartaceous, pinnately nerved, the secondary vein 4–6 pairs; upper surface dark green to green, sparely strigose, hairs 0.4–0.9 mm long, linear, cystoliths densely distributed, 0.2–0.25 mm long, fusiform; lower surface pale-green, densely strigose, hairs 0.5–0.7 mm long, linear, cystoliths absent; apex acuminate, entire; base shallowly cordate or the distal half semi-sagitate with auriculate limb not crossing the petiole to the opposite side; margin serrate, the basal 1/3 to 1/2 entire, ciliate, teeth 7–13 on acroscopic margin, 11– 17 on basiscopic margin. Inflorescences unisexual. Staminate inflorescences 8–10 × 5–8 mm, discoid, with two ellipsoidal parts, greenish, puberulous, hairs 0.15–0.4 mm long, linear; peduncle ca. 0.3 mm, puberulous, hairs 0.3– 0.4 mm long, linear; receptacle 4–4.5 × 2–3 mm, broadly oblong to oblong; bracts 1–1.5 mm long, apex with a subulate horn-like projection; bracteoles numerous, 2–3 mm long, narrowly oblong, cymbiform, membranous, semihyaline, apex mucronate, ciliate, margin entire, minutely ciliate. Pistillate inflorescences sessile to subsessile, up to 6 × 6 mm in diameter, ellipsoidal-discoid, white-green, hirsute outside, hairs 0.45–0.8 mm long, linear; receptacle 3–4 × 1.5–2 mm, broadly ovate to ovate; bracts 0.5–0.8 mm long, connate, the basal two with a subulate horn-like projection; bracteoles numerous, 0.5–1 × 0.2–0.5 mm, oblong to ovate, membranous, semihyaline, apex mucronate, long ciliate. Staminate flowers subtended by bracteoles; pedicels 1–1.5 mm long, glabrous; sepals 4, narrowly triangular, apex ciliate; stamens 4, inflexed. Pistillate flowers subtended by bracteoles, 0.75–1 mm; sepals 3, minute; staminodes 3 or 4; stigma penicillate; ovary glabrous, straight, ellipisoidal. Fruit not seen. Chromosome number, 2 n = 26.

Etymology: —Named for the hybrid origin.

Distribution: — Taiwan, found in low to medium altitude moist forest where it can form an important component of the ground story and adjacent to trails. Only 5-30 individuals were observed in each population and each population occupied less than 3 m 2.

Additional specimens examined: — TAIWAN. New Taipei City: Wulai District, Bafu trail , 24°45’53.42”N, 121°30’23.82”E, ca. 600 m, 22 August 2009, Y. H. Tseng 1135 ( TAI) , Honghe valley , 24°52’33.84”N, 121°31’41.67”E, ca. 250 m, 13 December 2009, Y. H. Tseng 1157 ( TAI) . Taoyuan County: Fuxing Town, Dongman forest trail , 24°49’04.86”N, 121°25’22.06”E, ca. 900 m, 28 August 2010, Y. H. Tseng 1180 ( TAI) . Miaoli County: Dahu Town, Mt. Malabang , 24°22’04.05”N, 120°54’25.31”E, ca. 1000 m, 4 September 2010, Y. H. Tseng 1185 ( TAI) . Taitung County: Daren Town, Anshuo , 22°17’10.86”N, 120°50’18.30”E, ca. 200 m alt., 9 February 2011, Y. H. Tseng 1198 ( TAI) .

Figures

FIGURE 1. Elatostema ×hybrida Tseng & Hu. A. Habit. B. Female inflorescence (ventral view). C. Female flower. D. Variation in female bracteoles, left: abaxial view, right: adaxial view. E. Male inflorescence (ventral view). F. Male flower, left: floral bud, right: blooming. G. Male bracteole. (A based on Y. H. Tseng1198; B–G based on Y.H.Tseng1117).

FIGURE 2. Photographs of E. ×hybrida. A. Habit. B. Male inflorescence. C. Female inflorescence. D. Male inflorescence (ventral view). E. Leaf base.