重慶樓梯草屬一新組和三新種

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)

樓梯草屬Elatostema J.R.& G.Forster

雌傘樓梯草組Sect.GynosciadionW.T.Wang,sect.nov.

Flores pistillati tepalis carentes, numerosi et densissimi in cymam ter vel quarter ramosam, receptaculo involucroque carentem dispositi. Cum his characteribus sectio nova haec a generisElatostematissectonibus ceteris omnibus praeclare distinguitur. In sectionibus ceteris. Sect.PellionioideW.T.Wang, Sect. Weddellia(H. Schr?ter) W.T.Wang, Sect.Elatostemateet Sect.AndrosyceWedd., flores pistillati plerumque numerosi in capitulum cum receptaculo involucroque et ramis carens dispositi.

Typus:E.femineocymosumW.T.Wang

Species unica, in Mt. Simianshan, Chongqing Shi endemica.

Etymology: gyne+sciadion: Greek for female and umbel, indicating the pistillate cymose inflorescences ofE.femineocymosumW.T.Wang.

雌花無花被片，多數(shù)極為密集的花組成3或4回分枝的聚傘花序，此花序不具花序托和總苞。根據(jù)這些特征可將本新組與樓梯草屬的所有其他組區(qū)別開；在其他組，疏傘樓梯草組Sect.PellionioidesW.T.Wang(雄花序?yàn)榫蹅慊ㄐ?，小葉樓梯草組Sect.Weddellia(H. Schr?ter) W.T.Wang，驟尖樓梯草組Sect.Elatostema和梨序樓梯草組Sect.AndrosyceWedd., 其等的雌花組成具花序托和總苞，不具分枝的頭狀花序[1～3]。

1種，特產(chǎn)重慶市四面山。

雌傘樓梯草 圖1

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

Perennial herb. Stem ca. 38 cm tall, above base ca. 2 mm acrass, glabrous, below the middle with 2 branches 8-13 cm long. Leaves all cauline, alternate, shortly petiolate or sessile, glabrous; blades thinly papery, lanceolate, oblong or oblanceolate, rarely ovate, (1.5-)4.5-11 cm×(0.5-)1.5-3.2 cm, at apex long acuminate, at base cuneate at leaf narrow side and auriculate at broad side, at margin densely denticulate, penninerved, secondary nerves at each side 4-6, flat, cystoliths dense, bacilliform, 0.2-0.3 mm long; petioles 0-1.2 mm long; stipules white, subulate or narrowly triangular, 2.2-3 mm long. Pistillate cymes or infructescences in pair axilliary, 5-10 mm broad, very shortly pedunculate, 3-4 times branched; branches not winged but often with white wings, the ultimate branches with very dense and numerous flowers or very dense and numerous achenes, and few small subulate bracts and hairs 0.7 mm long; pedicels very short and robust, ca. 0.1 mm long. Pistillate flower: Tepals absent; ovary white, oblong, ca. 0.4 mm long, glabrous; stigma with several white, thick and coarctate hairs 0.3 mm long. Achene white, ovoid, ca. 0.5 mm×0.35-0.4 mm, longitudinally and thinly 6-ribbed, glabrous. Staminate inflorescences and staminate flowers unknown.

重慶市(Chongqing Shi)：江津區(qū)，四面山，水口寺溝(jiangjin Qu,Simian Shan,Shuikousi Valley),alt. 757 m,闊葉林，溪邊，花序黃褐色(by stream in broad-leaved forest, inflorescences tawny)，2017-06-08，劉正宇，張軍等(Z.Y.Liu,J.Zhang,et al.)S-2201(holotype,PE)。

小葉樓梯草組Sect. Weddellia(H. Schr?ter) W.T.Wang

圓微葉樓梯草 圖2:A～C

ElatostemagyronanophyllumW.T.Wang, sp. nov. Fig.2:A-C

(Ser. Parva W.T.Wang)

Species nova haec est arcte affinisE.sinensiH. Schr?ter, a quo foliis minoribus, eorum laminis usque ad 5 cm longis, earum nervis secundariis utrinque 2-3, foliis redactis suborbicularibus, bracteis involucralibus pistillatis ca. 12 per capitulum triangularibus, flore pistillato tepalis duobus praedito, stigmate depresso-globoso differt. InE.sinensi, folia majora, eorum laminae usque ad 9.5 cm longae, earum nervi secundarii folii latere angustiore 4 et latere latiore 5-7, bracteae involucrales pistillatae numerosae per capitulum et lineares, flos pistillatus tepalis carens, stigma penicillatum, et folia redacta anguste elliptica sunt.

Perennial herb. Stems ca. 5, 12-21 cm tall, above base 1.5-2 mm across, above densely hirtellous, simple. Normal leaves shortly petiolate or sessile; blades papery, obliquely elliptic or oblong,(1-)2-5 cm×(0.7-)1.1-1.8 cm, at apex acuminate, rarely acute, at base cuneate at leaf narrow side and rounded at broad side, at margin dentate, adaxially sparsely strigulose, abaxially on nerves puberulous, semi-triplinerved, secondary nerves at each leaf side 2-3, cystoliths dense, inconspicuous, bacilliform, 0.15-0.5 mm long; petioles 0.3 mm long; stipules white, lineari-lanceolate, 1.5-3 mm long, glabrous. Reduced leaves opposite to normal leaves, orbitular or suborbicular, 2-4 mm in diam., entire rarely 3-lobulate. Pistillate capitulum

圖1 雌傘樓梯草 A.開花雌莖上部；B.雌聚傘花序；C.3朵雌花；D.瘦果Fig.1 Elatostema femineocymosum A. Upper part of flowering pistillate stem; B. Pistillate cyme; C. Three pistillate flowers; D. Achene(from holotype)

圖2 A～C.圓微葉樓梯草:A.開花雌莖中部和上部；B.雌頭狀花序(下面觀)；C.雌小苞片和2朵雌花 D～F.正宇樓梯草:D.營(yíng)養(yǎng)莖上部；E.開花雄莖；F.雄頭狀花序Fig.2 A-C.Elatostema gyronanophyllum:A. Middle and upper parts of flowering pistillate stem; B. Piatillate flowers(from holotype) D-F.E.zhengyuanum: D. Upper part of vegetative stem; E. Flowering staminate stem; F. Staminate capitulum(from holotype)

singly axillary, 2-5 mm in diam., subsessile, many-flowered; receptacle ca. 2 mm in diam., with a few hairs; involucral bracts ca. 12, greenish, membranous, triangular or narrow-triangular, 1.4 mm×1-2 mm, ciliate, apex corniculate, with green horn-like projections 0.25-0.5 mm long; bracteoles dense, white, ovate, 1 mm×0.6 mm, above long ciliate. Pistillate flower: Tepals 2, white, broadly ovate, 0.1 mm long, glabrous; ovary ellipsoid, 0.45 mm long, glabrous; stigma depressed-globose, ca. 0.15 mm in diam.

重慶市(Chongqing Shi)：江津市，四面山，大窩鋪(Jiangjin Qu,SimianShan,Dawopu), alt.1 085 m，闊葉林(in broad-leaved forest)，莖多汁，花腋生，黃綠色(stems juicy,fls. axillary,yellow-green),2017-05-16，劉正宇，張軍等(Z.Y.Liu,J.Zhang,et al.) S-1807(holotype,PE)。

本種在親緣關(guān)系方面與對(duì)葉樓梯草E.sinenseH.Schr?ter很相近，與后者的區(qū)別在于本種的葉較小，葉片長(zhǎng)達(dá)5 cm，每側(cè)具2～3條二級(jí)脈，退化葉圓形或近圓形，雌總苞具12枚三角形苞片，雌花具2花被片，柱頭扁球形。在對(duì)葉樓梯草，葉較大，葉片長(zhǎng)達(dá)9.5 cm，其二級(jí)脈在葉狹側(cè)4條，在寬側(cè)5～7條，退化葉呈狹橢圓形。雌總苞具多數(shù)條形苞片，雌花無花被片，柱頭畫筆頭狀[1]。

正宇樓梯草 圖2:D～F

ElatostemazhengyuanumW.T.Wang, sp. nov. Fig.2:D-F

(Sect.SublineariaW.T.Wang)

Species nova haec est arcte affinisE.simianshanicoW.T.Wang, a quo caulibus glabris nonnullis vegetativis, foliis normalibus praeditis nonnullis floriferis foliis minoribus praeditis, foliorum normalium laminis majoribus lanceolatis 3-9 mm longis, bracteis involucralibus staminatis oblanceolato-oblongis dorso haud carinatis recedit. InE.simianshanico, caules prope apicem puberuli, ei vegetativi nulli, foliorum laminae minores, usque ad 10 cm longae, cystolithi minores, 0.1-0.2 mm longi, stipulae etiam minores, subulatae, ca. 1.2 mm longae, et bracteae involucrales staminatae lineari-naviculares dorso carinatae sunt.

Perennial herbs. Stems vegetative or bearing flowers. Vegetative stem ca. 60 cm tall, above base ca. 2 mm across, glabrous, below 1-branched, above 6-leaved. Leaves of vegetative stem alternate, shortly petiolate, glabrous; blades papery, oblanceolate or oblong, 9-17 cm×2.4-4.6 cm, at apex long acuminate or subcuspidate, at base cuneate at leaf narrow side and auriculate at broad side, at margin densely dentibulate, penninerved, secondary nerves at leaf narrow side 5 and at broad side 6, flat, cystoliths dense, bacilliform, 0.3-0.8 mm long; petioles 0.8-2 mm long; stipules green, narrowly triangular, 3 mm long. Stem with staminate flowers ca. 35 cm tall, glabrous, with alternate small leaves lanceolate, 3-4 cm long and stipules white, lanceolate, 9 mm long, and on each leaf axil with a pair of staminate capitula. Staminate capitula 7-10 mm broad, ca. 6-flowered; peduncles 8-18 mm long, glabrous; receptacles small, 2-3 mm in diam., glabrous; involucral bracts ca. 7, 1-seriate, white, membranous, oblanceolate-oblong, 2-3 mm×1-1.5 mm, abaxially below apex long 1-corniculate, on apex sparsely ciliate; bracteoles ca. 2, narrowly linear, ca. 3 mm long, glabrous; pedicels 1.8-2.5 mm long, glabrous. Staminate flower buds bradly obovoid, 2.2-2.5 mm in diam., subglabrous, on apex 5-corinculate, with horn-like projections 1.5-2 mm long. Pistillate capitula and pistillate flowers unknown.

重慶市(Chongqing Shi)：江津區(qū)，四面山，自朝陽(yáng)關(guān)至大黃溝途中(Jiangjin Qu,Simian Shan,on the way from Chaoyangguan to Dahuang valley),alt. 1 026 m，闊葉林，溪邊，花白色帶紫紅色(by stream in broad-leaved forest,fls. white, tinged with purplish red),2017-03-28,劉正宇，張軍等(Z.Y.Liu,J.Zhang et al.) S-1204(holotype,PE)。

本種在親緣關(guān)系方面很接近四面山樓梯草E.simianshanicumW.T.Wang,與后者的區(qū)別在于本種的莖無毛，有時(shí)為營(yíng)養(yǎng)莖，具正常葉，有時(shí)具花，具較小葉，葉片(長(zhǎng)達(dá)17 cm)、鐘乳體(長(zhǎng)0.3～0.8 cm)和托葉(披針形，長(zhǎng)3～9 mm)均較大，雄頭狀花序的總苞苞片倒披針狀長(zhǎng)圓形，背面無雞冠狀突起。在四面山樓梯草，莖近頂部被短柔毛，無營(yíng)養(yǎng)莖，葉片(長(zhǎng)達(dá)10 cm)、鐘乳體(長(zhǎng)0.1～0.2 mm)和托葉(鉆形，長(zhǎng)1.2 mm)均較小，雄頭狀花序的總苞片條狀船形，背面有1條雞冠狀突起[2]。

本種以劉正宇先生的名字命名。劉正宇先生多年來在重慶市金佛山、四面山等多地采集到大量植物標(biāo)本，為重慶市植物區(qū)系的研究做出重要貢獻(xiàn)。

致謝深切感謝劉正宇先生惠贈(zèng)珍貴植物標(biāo)本，以及孫英寶先生為本文繪圖。