SynopsisHybridisation in Equisetum in Britain and Ireland is examined in respect of the exceptional numbers of hybrids present, their geographic and ecological distribution, their formation and subsequent spread.It is concluded that the moist oceanic climate and relative paucity of competing species in the British and Irish floras in post-glacial time have created uniquely favourable conditions for the formation and subsequent success of hybrid horsetails, promoting both the short-term persistence of weaker hybrids, and the extremly long-term persistence of others.The taxonomic inter-relations of parental combinations which have formed ecologically successful hybrids are discussed.
How mutualisms influence the coexistence of competing species