Karyotypes and Relationships among Bolandra, Boykinia, Peltoboykinia, and Suksdorfia (Saxifragaceae: Saxifrageae)

Bolandra, Boykinia, and Suksdorfia are all characterized by x 7 and have essentially identical Hy-banded patterns and gross morphological karyotypes. Cytological data suggest a close relationship between Boykinia intermedia and B. major, both of which are unusual in possessing 2n = 28. Karyotypes of Bolandra, Boykinia, and Suksdorfia appear to be indistinguishable from those re- ported earlier for Sullivantia. Peltoboykinia differs from Bolandra, Boykinia, Suksdorfia, as well as Sulli- vantia, in having x 11. Peltoboykinia also exhibits a distinctive karyotype that readily differentiates it from these genera. Karyotypic data suggest that Bolandra, Boykinia, Suksdorfia, and Sullivantia form a natural group. These genera are united also by several morphological features, including axile placentation and a monotelic inflorescence. Data from flavonoid chemistry and the host preferences of Puccinia rusts also indicate a close relationship among these four genera. Although Peltoboykinia is clearly allied with Bolandra, Boykinia, Suksdorfia, and Sullivantia, on the basis of cytological evidence its closest affinities may lie elsewhere in Saxifragaceae, perhaps with Saxifraga.