Hypericum maculatum subsp. obtusiusculum (Nomenclature)
Stems with subsidiary lines present or sometimes partly (or wholly?) absent. Leaves with rather dense tertiary venation (somewhat laxer than in subsp. maculatum); laminar gland dots pale, dense to very sparse or absent. Inflorescence branches widely ascending, making an angle of c. 50° with stem. Flowers 25-30 mm in diam. Sepals broadly to narrowly ovate, with apex finely eroded-enticulate or rarely entire. Petals usually distally unilaterally crenate with marginal black glands in depressions?; laminar glands pale and black or rarely only pale, linear to striiform and sometimes punctiform.
Styles 1-2 ´ ovary. 2n = 32 (Robson, 1956, 1957, 1958a).
Montane regions and valleys in the Alps, lowland further north, in meadows, rough pasture and damp woods; 0-c. 850 m.
North-west Europe east to western Germany and Bohemia (except most of western Scotland), valleys of the Alps east to Styria, western Hungary. Introduced into Canada (British Columbia).
The presence of linear glands (sometimes pale) in the petals and the greater frequency of pale glands in the leaves suggest that subsp. obtusiusculum has evolved from subsp. immaculatum, not, as I thought from my own observations and experiment, from subsp. maculatum. The plant obtained by colchicine doubling of the chromosomes (Robson, 1957, 1958a) had broad leaves, broad entire sepals and black petal laminar glands, as was to be expected starting from var. maculatum; but the inflorescence branching was wide and the petal glands (as far as I can remember in the absence of a specimen) were mostly linear. The presence of broad entire sepals in this experimental plant, in Leers's (lost) type of H. dubium, and in a recently collected specimen from SW. Scotland suggests that the frequent occurrence today of narrow oblong sepals and incomplete subsidiary stem lines may have resulted from recent introgression from H. perforatum.
Schwarz (1965) recorded 2n=16 for H. erosum (= subsp. obtusiusculum) and 2n=24 for its hybrid with H. perforatum, adding that all his material gave the diploid number. Unless his results are duplicated in the future (which would necessitate a revision of the view adopted here), one must assume that his material was misidentified.
According to Stafleu & Cowan (1979), Leers' herbarium was taken to Russia (early in the nineteenth century?) and subsequently partly destroyed and partly lost. His description (apart from the ovate entire sepals) and the location of Herborn are both consistent with his plant's belonging to subsp. obtusiusculum; and broad entire sepals are not unknown in subsp. obtusiusculum, having been found in Kirkcudbrightshire, SW. Scotland (see record, p. ), and they were recorded by Tourlet (1903). They also occurred in a plant of subsp. maculatum in which the chromosomes had been doubled by colchicine treatment (Robson, 1956, 1957, 1981). Schinz, in the paper cited above, discussed the name H. dubium but treated it as a synonym of H. quadrangulum in his sense, i.e. H. maculatum Cr. Fröhlich (1911) also regarded H. dubium as a synonym of H. maculatum (i.e. subsp. typicum).
My preliminary selection of lectotype for H. desetangsii var. [b] imperforatum Bonnet, Lloyd's specimen from Loire-Inférieure [Loire-Atlantique], was published by Mártonfi et al. (1999: 339) as "Robson, in prep.". Neither they nor I have seen this specimen, and the more widely distributed Bonnet exsiccata cited above would seem to be a more appropriate choice.
Tourlet describes H. quadrangulum subsp. quadrangulum on the same page in the sense of H. tetrapterum Fr.
Schinz, "in order not to provide an unnecessary synonym and in support of the Rules of Nomenclature", named this form [sic] (H. quadrangulum subsp. erosum var. epunctatum Schinz) epunctatum.
Note: none of Fröhlich's combinations of his formae under subsp. obtusiusculum in 1915 (p. 221) were effective.