Roberts A V
Department of Agricultural Botany, Reading University, Reading RG6 2AS.
Bot J Linn Soc. 1977 Jun;74(4):309-328. doi: 10.1111/j.1095-8339.1977.tb01184.x. Epub 2008 Jun 28.
The morphology of twelve species of is described and similarities between these species are assessed. Possible origins of the tetraploid species from diploid species are indicated on grounds of comparative morphology. The wild origins of living and herbarium specimens are given in order to supplement published data on geographical distribution. Meiosis in pollen mother cells, viability of pollen grains at anthesis and ability to set seed was studied in several F hybrids: no indication of complete or even partial sterility was found. Reproductive isolation is therefore unlikely to be maintained by reduced fertility of interspecific hybrids. Three species are reduced to synonymy with three other species, being retained as subspecific taxa. Two species are transferred from section to section
描述了12个物种的形态，并评估了这些物种之间的相似性。基于比较形态学指出了四倍体物种可能来自二倍体物种的起源。给出了活体标本和标本馆标本的野生来源，以补充已发表的地理分布数据。在几个F杂种中研究了花粉母细胞的减数分裂、花期花粉粒的活力和结实能力：未发现完全或部分不育的迹象。因此，种间杂种育性降低不太可能维持生殖隔离。三个物种被归为与其他三个物种同义，作为亚种分类群保留。两个物种从一个组转移到另一个组
