Hypericum xdesetangsii (Nomenclature)
Stems almost completely 4-lined to 2-lined. Leaves broadly ovate or broadly elliptic or ovate -oblong to linear; tertiary reticulate venation dense to lax; pale laminar glands dense (especially in upper leaves) to very few. Sepals broadly elliptic to linear-lanceolate, obtuse to acuminate, entire or ± eroded-denticulate to subfimbriate. Petals with black laminar glands rather numerous to few, mostly linear to mostly punctiform, or absent; black marginal glands present. Capsule with vittae all linear and vertical or some lateral, oblique and irregular to elongate-vesicular.
Intermediate between the parents, but back-crossing to both at the tetraploid level of H. maculatum (subsp. obtusiusculum) has resulted in a complete series of intermediate forms of H. ´desetangsii nothosubsp. desetangsii (cf. Crackles, 1990). At the diploid level (subsp. maculatum), two distinct forms of nothosubsp. carinthiacum occur, one triploid (2n=24) (H. maculatum _ (n=8) ´ H. perforatum _ (n=16) or, probably rarely but conceivably, H. perforatum _ (n=16, i.e. reduced) ´ H. maculatum _ (n=8)), the other pentaploid (2n=40) (H. perforatum _ (n=32, i.e. unreduced) ´ H. maculatum _ (n=8)). In the cross with subsp. maculatum (nothosubsp. carinthiacum), these forms are at least sometimes distinguishable (respectively nothoforma maculatiforme and nothoforma perforatiforme); but in the cross with the presumed diploid subsp. immaculatum (nothosubsp. balcanicum), no distinct morphological forms are apparent and no chromosome counts have yet been made. As the specimens with this alleged parentage are intermediate between the parents, however, they are likely to be triploid. See Noack (1939) for a discussion of the cytology, but not the nomenclature.
Although records are scattered, distribution of the hybrids would appear to be confined to the areas of distribution overlap of the parents; but vegetative propagation and (in nothosubsp. desetangsii) partial fertility of the hybrids has sometimes resulted in their occurrence in the absence of one or both parents.
It is not certain from the description whether ?H. ´mixtum Du Moulin is an earlier synonym of H. ´desetangsii or a later synonym of H. maculatum Cr. (cf. Mártonfi, Rep_ák & Mihoková, 1996). Fröhlich (1911: 568) was unable to find the type specimen in W; so, unless or until it is discovered and proves to be H. ´desetangsii, it seems best to maintain the well known name.