蕨类植物蜈蚣草在江苏分布的新记录及其传播机制分析

报道了近期在江苏省南京市中华门城墙上发现的蜈蚣草(Pteris vittataL.)天然种群,共计约101株蜈蚣草生长在高大墙体上部的砖缝中及中下部的条石缝隙中,分布面积共约70m2.这些长势良好的蜈蚣草绝大多数都是成年个体,羽片背面都具有线形孢子囊群.由于蜈蚣草在江苏省并没有自然生长与分布,并且它的孢子等繁殖体也很难依靠风、水等自然媒介传播至南京中华门城墙这一孤岛"状生境中,而有关历史资料显示,600多年前在修筑包括中华门城墙在内的南京明城墙过程中,所需的城砖分别在江西、安徽、湖北等省烧制,并通过水路运送至南京.综合分析认为,中华门城墙上的蜈蚣草种群可能最初来源于这些城砖运输过程中所携带的蜈蚣草孢子.

New Record of Pteris vittata L. From Jiangsu Province and a Tentative Analysis of Its Dispersal Mechanism

Natural populations of Pteris vittata L.were recently found on the city wall of the jar-like forts within Zhonghua Gate,the largest gate of Nanjing city wall of the Ming Dynasty,Nanjing,the capital of Jiangsu Province,East China.In total,ca.101 individuals of P.vittata L.grew well in the crevices between bricks of the upper part of the city wall,or in those between stone blocks of the middle and lower parts of the wall,and their distribution areas approximately reached 70 m2.Most individuals of this fern species were adults with fully developed linear sori on the abaxial edges of the pinnae.Since no natural population of P.vittata L.was ever reported in Jiangsu Province previously,and its propagules,such as spores,were rather difficult to be dispersed through wind or water to Zhonghua Gate,which could be considered as an "isolated island" within Nanjing City.However,the historical data indicated that the bricks for constructing the famous Nanjing City wall of the Ming Dynasty were made in other provinces with natural populations of P.vittata L.,e.g.Jiangxi,Anhui,and Hubei provinces,and then they were transported to Nanjing on water path.Consequently,a tentative conclusion is proposed here that the new record of P.vittata L.in Zhonghua Gate of Nanjing City could be initially originated from the spores conveyed incidentally to Nanjing during the transportation of the bricks from other provinces more than 600 years ago.