~40% of plant families: ~16% of plant genera %
||Yakimowski SB, Rieseberg LH. The role of homoploid hybridization in evolution: a century of studies synthesizing genetics and ecology. Am J Bot. 2014 Aug101(8):1247-58. doi: 10.3732/ajb.1400201 p.1248 left column 3rd paragraphPubMed ID25156978
||Whitney K. D., J. R. Ahern, L. G. Campbell, L. P. Albert, and M. S. King. 2010. Patterns of hybridization in plants. Perspectives in Plant Ecology, Evolution and Systematics 12: 175–182. link
||Abstract: "[Investigators] revisit Stebbins' views on the frequency of hybridization, the evolution of hybrid sterility, and the evolutionary importance of transgressive segregation, introgression, and homoploid hybrid speciation in the context of contemporary evidence. Floristic surveys indicate that ∼10% of plant species hybridize, suggesting that natural hybridization is not as ubiquitous as Stebbins argued."
||P.1248 left column 3rd paragraph: "The other important observation from floristic surveys is that hybridization is unevenly distributed taxonomically (Ellstrand et al., 1996), with hybrids reported in approximately 40% of families and 16% of genera in the most comprehensive analysis (primary source). There is a strong phylogenetic signal (λ) in the propensity of plant genera to hybridize: λ = 0.93 based on an ordinal level phylogeny, where 0 = no phylogenetic signal and 1 = complete phylogenetic dependence (primary source)."