Leonurus intermedius, species nova – with additional notes on some other Leonurus taxa

Leonurus intermedius Holub from the L. cardiaca agg. (Leonurus L. sect. Leonurus) is described as a new species, taxonomically situated between L. cardiaca L. and L. villosus Dum.-d'Urv.; the type locality is in Central Bohemia. Its distribution in the Czech Republic is given on the basis of a revision of the material in the herbaria PR and PRC. The taxon evolved most probably by hybridogenesis between L. cardiaca and L. villosus; it is known mostly from this century, i.e. from the period after immigration of L. villosus to Central Europe. The kind of indumentum is the most important distinguishing character among the members of L. cardiaca agg.; a determination key for three Central European taxa of the aggregate is given. A list of localities of L. intermedius from the Czech Republic was compiled including 88 localities, arranged after the phytogeographical division of that area. A new variety is described in L. cardiaca L. - var. hirtella Holub. The closest relationship of this species seems to be to the Eurasiatic continental species L. glaucescens Bunge. Nomenclatural problems of L. villosus are mentioned but not finally solved. Finding of two herbarium sheets with plants of L. japonicus Houtt. from Bohemia is mentioned in an additional note (cultivated plants?).