頭序冷水花屬，廣西蕁麻科一新屬

王文采

(中國(guó)科學(xué)院植物研究所，系統(tǒng)與進(jìn)化植物學(xué)國(guó)家重點(diǎn)實(shí)驗(yàn)室，北京 100093)

頭序冷水花屬，廣西蕁麻科一新屬

王文采

(中國(guó)科學(xué)院植物研究所，系統(tǒng)與進(jìn)化植物學(xué)國(guó)家重點(diǎn)實(shí)驗(yàn)室，北京 100093)

描述了自廣西發(fā)現(xiàn)，隸屬蕁麻科假樓梯草族的一新屬，頭序冷水花屬。此屬與冷水花屬在親緣關(guān)系方面甚為接近，與后者的區(qū)別在于本屬的雌花序頭狀，具長(zhǎng)圓形盤狀花序托，在其上生多數(shù)苞片和雌花。此外，此屬也與假樓梯草屬近緣，與后者的區(qū)別在于本屬的雌頭狀花序無花序梗，具對(duì)折的長(zhǎng)圓形花序托，無總苞，雌花被片頂端既不成兜狀，也無角狀突起。

蕁麻科；頭序冷水花屬；新屬；廣西

圖1 頭序冷水花a.雌莖頂部；B.雌頭狀花序(側(cè)面觀)；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)

頭序冷水花屬

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.

本屬的葉對(duì)生，雌花被片離生，雌蕊具畫筆頭狀柱頭，因此與也具這些特征的冷水花屬(Pilea)在親緣關(guān)系方面甚為相近，其與后者的區(qū)別在于本屬的雌花序頭狀，具長(zhǎng)圓形盤狀花序托，多數(shù)苞片和雌花生在花序托的近軸面上；而在冷水花屬，雌花序?yàn)榫蹅慊ㄐ蚧蚓蹅銏A錐花序，無花序托，苞片互生。此外，本屬的雌花序?yàn)轭^狀花序，因此與也具此特征的假樓梯草屬(Lecanthus)有相近的親緣關(guān)系，其與后者的區(qū)別在于本屬的雌頭狀花序無花序梗，具對(duì)折的長(zhǎng)圓形花序托，花序托邊緣無總苞，雌花被片頂端不呈兜狀，也無角狀突起；而在假樓梯草屬，雌頭狀花序具長(zhǎng)花序梗和圓盤狀花序托，在花序托邊緣具總苞，雌花被片頂端呈兜狀，并在背面頂端之下常有一角狀突起[1～3]。毫無疑問，此二進(jìn)化屬，頭序冷水花屬和假樓梯草屬，均是起源自原始的冷水花屬[1]。

頭序冷水花 圖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.

廣西(Guangxi): 靖西縣(Jingxi Xian), alt. 600 m，縣城附近，石灰?guī)r山蜆木林下(under Burretiodendron forest in limestone hill near city)，植物高70 cm(pl.70 cm tall),1973-08,王獻(xiàn)溥，無號(hào)(Wang Xian-pu,sine num.)(holotype,PE).

致謝深切感謝孫英寶先生為本文繪圖。

1.陳家瑞.中國(guó)蕁麻科冷水花屬的研究[J].植物研究,1982,2(3):1-32.

2.陳家瑞.Pilea和Lecanthus.于中國(guó)植物志[M].北京:科學(xué)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，研究員，中國(guó)科學(xué)院院士，從事有花植物分類學(xué)研究。

2015-02-15

Q949.737.5

A

10.7525/j.issn.1673-5102.2016.02.002