Department of Botany, Natural History Museum, London SW7 5BD, UK.
Am J Bot. 2006 Mar;93(3):426-41. doi: 10.3732/ajb.93.3.426.
The revision of species-rich genera underpins research and supports the sustainable use and monitoring of biological diversity. One fifth to one quarter of the diversity of all seed plant species occurs in such genera, but difficulties with the revision of species-rich genera has resulted in many of them being ignored since the late 1800s. Pilea, with 600-715 species is in need of revision. The only realistic approach is in manageable subunits, which requires confirmation of monophyly and identification of monophyletic subdivisions. Parsimony analyses of trnL-F, ITS, and morphology data were used to test the monophyly of, and explore intrageneric relationships within, Pilea. Analysis of trnL-F data confirms and recovers two morphologically diagnosable monophyletic clades that include all of the taxa within Pilea. Overlaying geographic distribution on a most parsimonious tree indicates a strong association between geography and phylogenetic relatedness. It is suggested that a strategic revision within the framework of morphologically and geographically diagnosable units might enable the revision of the group using an iterative approach. Analysis of the outgroup taxa supports the inclusion of Poikilospermum within the Urticaceae and suggests that the Urticaceae tribes could be placed into two clades that are supported by floral morphology.
修订物种丰富的属是研究的基础，有助于支持生物多样性的可持续利用和监测。所有种子植物物种的多样性中有五分之一到四分之一发生在这些属中，但由于修订物种丰富的属存在困难，自 19 世纪末以来，许多属都被忽视了。苎麻属有 600-715 个物种，需要修订。唯一现实的方法是在可管理的亚单位中，这需要确认单系性并确定单系性细分。使用 trnL-F、ITS 和形态学数据的简约分析来检验苎麻属的单系性，并探索属内的种间关系。trnL-F 数据分析证实并恢复了两个形态上可识别的单系群，它们包含了苎麻属内的所有分类群。将地理分布叠加在最简约树上表明地理和系统发育关系之间存在很强的关联。有人建议，在形态学和地理上可诊断的单位框架内进行战略性修订，可能会使该组能够采用迭代方法进行修订。对外群分类群的分析支持将波希米亚松属归入荨麻科，并表明荨麻科族可以分为两个由花形态支持的分支。
