Crossophyllum (Nomenclature)
Perennial herbs up to 0.55 m m tall, glabrous, not glaucous, with stems erect from decumbent to prostrate and rooting base, radiating from taproot, unbranched below inflorescence or usually branched at the base and sometimes from intermediate nodes, with dark (black or reddish) to amber or pale glands on leaves, sepals and anthers and sometimes stem and petals. Stem narrowly 2(4)-lined to terete, eglandular or with dark (black and amber to reddish) glands on raised lines and surface. Leaves opposite, decussate, sessile or subamplexicaul, free, persistent, chartaceous, usually auriculate; lamina entire or gland-fringed, with venation pinnate; laminar glands pale and sometimes black and sessile or on long cilia, punctiform or sometimes absent (in 2. H. aucheri). Inflorescence 1–c. 50-flowered, with branching mainly monochasial, without or with 1-4 subsidiary branches; bracts and bracteoles auriculate (except in 2. H. aucheri). Flowers stellate, homostylous. Sepals 5, free or slightly connate, usually ± imbricate, persistent, erect in fruit, with margin glandular-laciniate, -ciliate or -tuberculate; veins 3–5; laminar glands pale, linear to punctiform, and sometimes black, punctiform; marginal glands black or amber, intramarginal or on denticles to fimbriae, irregular. Petals 5, persistent, erect but not twisting after flowering, without apiculus; margin entire or crenate to glandular-ciliate; laminar glands pale and sometimes black, linear to punctiform; marginal glands black, regular or distal, sometimes almost absent. Stamen fascicles ‘3’(5), persistent, with stamens totalling 30–80; anther gland amber or black (H. thasium); pollen type X. Ovary with 3(5) axile placentae, each ∞-ovulate; styles 3(5), diverging; stigma narrow. Capsule 3(5)-valved, subcoriaceous, with valves longitudinally narrowly vittate. Seeds cylindric, not carinate or appendiculate; testa shallowly reticulate to foveolate-scalariform.
BASIC CHROMOSOME NUMBER (X). 8; ploidy 2.
Open or lightly wooded sites on calcareous or siliceous soil, dry or more rarely humid; 0–2300 m.
Bulgaria (south), Greece (eastern Makedhonia, Thrakia, Thasos), Turkey (north and west-central), Georgia, Russia (northern Caucasus and Dagestan).
4 species.
Of the four species included here in Sect. Crossophyllum, two (H. adenotrichum and H. orientale) constituted Spach’s original section, both having ‘fringed leaves’ (to which the sectional name refers) and foliar auricles. Hypericum thasium was placed in its own section by Boissier (1867) on account of its 5-merous gynoecium, while H. aucheri was originally included in Sect. 18. Taeniocarpium by Jaubert & Spach (1842) and later allocated to Sect. Euhypericum subsect. Homotaenium by Keller (1893, 1925). Noting certain resemblances between H. aucheri and the H. humifusum group (Sect. 14. Oligostema), I included it in that section (Robson, 1977). However, this species is geographically anomalous in Sect. Oligostema; and it later became clear to me that the above-mentioned four species formed an eastern group, sister to the mainly western Sect. Oligostema (cf. Fig. 10) and usually differing from it in having an amber, not black anther gland. Hypericum aucheri can then be seen to be a close relative of H. thasium with a reduced habit and the trimerous gynoecium normal for the group, whilst the gland-fringed leaves and foliar auricles typical of Sect. Crossophyllum are both foreshadowed in the variation of H. thasium, the 5-merous gynoecium of that species being seen as a local specialisation, not an ancient survival.