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Language: English with bilingual summary in English and Spanish
Northern Mexican Crataegus are arranged in four sections: Parvifoliae, Mexicanae, Crus-galli, Coccineae. Five new series are recognised in sect. Coccineae. Thirteen species are recognised of which six are new. Also, several new subspecies, varieties and a new name are made. One hundred seventy-one specimens were scored in triplicate, generating 513 OTUs and then morphometric analysis using 50 characters for fruiting material or 44 characters for flowering material was undertaken. Cluster analysis, principal components analysis (PCA) and randomization tests were used in order to expose and validate group structure. Nearly all the postulated taxa were readily differentiated in this manner, the large character suites used underlining the robustness of the results. Some of the less clear separations were resolved by further analysis using only those characteristics high-ranking in the PCAs. However, in no case were less than 17 characters required to separate taxa eventually recognised. The paper also discusses the biogeography and ethnobotany of Mexican Crataegus, and provides keys to taxa, descriptions and illustrations.