头序冷水花属，广西荨麻科一新属

王文采

(中国科学院植物研究所，系统与进化植物学国家重点实验室，北京 100093)

头序冷水花属，广西荨麻科一新属

王文采

(中国科学院植物研究所，系统与进化植物学国家重点实验室，北京 100093)

描述了自广西发现，隶属荨麻科假楼梯草族的一新属，头序冷水花属。此属与冷水花属在亲缘关系方面甚为接近，与后者的区别在于本属的雌花序头状，具长圆形盘状花序托，在其上生多数苞片和雌花。此外，此属也与假楼梯草属近缘，与后者的区别在于本属的雌头状花序无花序梗，具对折的长圆形花序托，无总苞，雌花被片顶端既不成兜状，也无角状突起。

荨麻科；头序冷水花属；新属；广西

图1 头序冷水花a.雌茎顶部；B.雌头状花序(侧面观)；C. 3苞片；D. 2苞片和2雌花Fig.1 Metapilea jingxiensisa. Apical part of pistillate stem; B. Pistillate capitulum(lateral view); C. 3 bracts; D. 2 bracts and 2 pistillate flowers(from holotype)

头序冷水花属

MetapileaW. T. Wang, gen. nov.

(TribeLecantheaeWedd.)

Ob folia opposita, tepala pistillata libera et florem pistillatum stigmate penicillato praeditum genus novum hoc est arcte affinePileaeLindl., quae inflorescentiis pistillatis cymosis vel cymoso-paniculatis receptaculis carentibus et bracteis alternatis praeditis differt. Etiam ob inflorescentias pistillatas capitatas id est affineLecanthoWedd., qui capitulis pistillatis longe pedunculatis receptacula orbiculari-discoidea haud conduplicata et involucra gerentibus, tepalis pistillatis apice cucullatis dorso infra apicem saepe 1-corniculatis recedit, et cumLecanthoex genere primitivoPileasine dubio simul oriundum fuit.

Herb perennial, dioecious. Stem erect, glabrous. Leaves opposite, petiolate, glabrous; blades broadly elliptic, trinerved. Staminate inflorescences and staminate flowers unknown. Pistillate inflorescences capitate, singly axillary, sessile; receptacle oblong, conduplicate, at margin lacking involucre; bracts numerous, dense, with numerous pistillate flowers borne on adaxial surface of receptacle. Pistillate flower: tepals ca. 2, lanceolate-linear, at apex neither cucullate, nor corniculate; pistil with straight, ellipsoidal or subglobose ovary and sessile, long penicillate stigma.

Type:MetapileajingxiensisW. T. Wang.

Species 1, endemic to Jingxi Xian, Guangxi Autonomous Region.

本属的叶对生，雌花被片离生，雌蕊具画笔头状柱头，因此与也具这些特征的冷水花属(Pilea)在亲缘关系方面甚为相近，其与后者的区别在于本属的雌花序头状，具长圆形盘状花序托，多数苞片和雌花生在花序托的近轴面上；而在冷水花属，雌花序为聚伞花序或聚伞圆锥花序，无花序托，苞片互生。此外，本属的雌花序为头状花序，因此与也具此特征的假楼梯草属(Lecanthus)有相近的亲缘关系，其与后者的区别在于本属的雌头状花序无花序梗，具对折的长圆形花序托，花序托边缘无总苞，雌花被片顶端不呈兜状，也无角状突起；而在假楼梯草属，雌头状花序具长花序梗和圆盘状花序托，在花序托边缘具总苞，雌花被片顶端呈兜状，并在背面顶端之下常有一角状突起[1～3]。毫无疑问，此二进化属，头序冷水花属和假楼梯草属，均是起源自原始的冷水花属[1]。

头序冷水花 图1

MetapileajingxiensisW. T. Wang, sp. nov. Fig.1

Herb perennial, dioecious. Stem ca. 70 cm tall, near apex ca. 2.2 mm across, glabrous, longitudinally shallowly 6-sulcate. Leaves opposite, petiolate, glabrous, those of the same pair equal or slightly unequal in size; blades papery, broadly elliptic, 6-8×3-4 cm, apex shortly acuminate, base cuneate or broadly cuneate, margin at each leaf side near apex minutely 2-3-denticulate; nervation trinerved, with basal nerves on both surfaces flat and with 2-3 pairs of incospicuous lateral nerves; cystoliths dense, conspicuous, bacilliform, 0.2-0.5 mm long; petioles 3-5 mm long; stipules lanceolate-linear, ca. 14×3 mm. Pistillate capitula singly axillary, sessile; receptacle transversely oblong, ca. 3×9 mm, conduplicate, glabrous; bracts numerous, dense, brown, oblanceolate, spathulate or linear, 0.4-0.8 mm long, glabrous, rarely above sparsely ciliolate, the larger bracts 1-nerved and often at apex apiculate. Pistillate flower shortly pedicellate; tepals ca. 2, brown, linear, 0.2-0.5 mm long, glabrous; pistil brown; ovary broadly ellipsoidal, ca. 0.4 mm long, or subglobose, ca. 0.3 mm in diam., glabrous; stigma long penicillate, with hairs dense, slender, 1-1.5 mm long.

广西(Guangxi): 靖西县(Jingxi Xian), alt. 600 m，县城附近，石灰岩山蚬木林下(under Burretiodendron forest in limestone hill near city)，植物高70 cm(pl.70 cm tall),1973-08,王献溥，无号(Wang Xian-pu,sine num.)(holotype,PE).

致谢深切感谢孙英宝先生为本文绘图。

1.陈家瑞.中国荨麻科冷水花属的研究[J].植物研究,1982,2(3):1-32.

2.陈家瑞.Pilea和Lecanthus.于中国植物志[M].北京:科学出版社,1995,23(2):57-160.

3.Friis I.Urticaceae[M].//Kubitzki K,Rohwer J G,Bittrich V,et al.The families and genera of vascular plants.Berlin:Springer-Verlag,1993,2:612-630.

Metapilea,aNewGenusofUrticaceaefromGuangxi

WANG Wen-Tsai

(State Key Laboratory of Systematic and Evolutionary Botany,Institute of Botany,Chinese Academy of Scienses,Beijing 100093)

A genus belonging to the tribeLecantheaeWedd. of the family Urticaceae,Metapilea, is described as new from Guangxi Autonomous Region. This genus is closely related toPileaLindl., and from the latter differs in its piatillate capitate inflorescences with oblong discoid receptacles and with numerous bracts and pistillate flowers borne on the adaxial surface of receptacle. Besides, it is also related toLecanthusWedd., and from the latter differ in its sessile pistillate capitula with conduplicate oblong receptacles and lacking involucres and in its neither cucullate nor corniculate pistillate tepals. Without doubt, these two advanced genera,MetapileaandLecanthus, have both originated from the primitive genusPilea.

Urticaceae;Metapilea;new genus;Guangxi

王文采(1926—)，男，研究员，中国科学院院士，从事有花植物分类学研究。

2015-02-15

Q949.737.5

A

10.7525/j.issn.1673-5102.2016.02.002