Patterns of rarity in the native British flora

We have combined published data on ecology and conservation status with phylogenetic information for all native British angiosperms. We use this information to explore patterns of threat with regard to taxonomy, ecology and life history. Threat status is significantly clumped among orders. However among genera, we identify only Limonium (sea lavenders) and Sorbus (whitebeams) as containing more threatened species than expected under a hypergeometric model, and we discuss the artefactual reasons for this finding. We present a table of Britain's 10 most threatened families according to this statistic. Threat status is also strongly clumped across habitat types using two published schemes. In an analysis excluding artificially influential genera, we identify the 'arable and horticultural', 'montane', 'inland rock', and 'supra-littoral sediment' habitats as containing more threatened species than would be expected under a hypergeometric model and discuss these results. Finally, we use phylogenetically independent contrasts to show that threat status is correlated with small size, low fecundity, and insect rather than wind pollination for the native British flora. (C) 2004 Elsevier Ltd. All rights reserved.