Géneros de organismos asociados: Xanthium [352 taxones], Xanthoceras [1 taxon], Xanthogalum [2 taxones], Xanthoparmelia [1 taxon], Xanthophyllum [9 taxones], Xanthoria [58 taxones], Xanthoriicola [4 taxones], Xanthorrhoea [5 taxones], Xanthosoma [86 taxones], Xanthoxalis [17 taxones], Xantolis [1 taxon], Xenodochus [1 taxon], Xenosporium [65 taxones], Xenostigme [3 taxones], Xenostomella [2 taxones], Xeranthemum [51 taxones], Xerapetalis [1 taxon], Xerocomus [1 taxon], Xeromphalina [2 taxones], Xeromphis [7 taxones], Xerophyllum [2 taxones], Xerophyta [2 taxones], Ximenia [31 taxones], Xolisma [1 taxon], Xylaria [52 taxones], Xylia [7 taxones], Xylobolus [3 taxones], Xylocarpus [8 taxones], Xylogramma [1 taxon], Xylopia [179 taxones], Xylosma [29 taxones], Xylosphaera [2 taxones], Xylostroma [2 taxones], Xylotheca [31 taxones], Xymalos [61 taxones], Xyris [2 taxones], Xystozukalia [9 taxones]