Perennial herb 0.07–0.32 m tall, erect from decumbent to prostrate rooting base, with stems numerous, spreading and branching from taproot, otherwise not branching below inflorescence. Stems narrowly 2-lined, eglandular; internodes 4–10 mm, shorter than leaves. Leaves sessile, ascending; lamina 7–32 × 2.2–5 mm (excluding auricles), linear to oblong or oblanceolate, slightly paler beneath, thinly chartaceous; apex rounded to obtuse, margin plane, glandular-ciliate, base cuneate with paired glandular-ciliate auricles; venation: 3 main veins from lower 1/4 to 2/5 of midrib, not visibly branched; laminar glands pale, punctiform, dense and sometimes black, scattered and 1–2 subapical; marginal glands black, on long cilia or fimbriae, not co-planar. Inflorescence 3–7(–23)-flowered, from 1–3 nodes, without flowering branches below, the whole obpyramidal to cylindric; bracts and bracteoles elliptic to oblong, auriculate and gland-fringed like leaves. Flowers 20–c. 32 mm in diam.; buds ellipsoid, obtuse. Sepals equal to subequal, not imbricate, basally slightly connate, 6–9 × 1–2 mm (excluding fimbriae), narrowly lanceolate to narrowly oblong or linear, subacute to obtuse, irregularly glandular-fimbriate; veins 3, obscurely branched; laminar glands few, pale and/or black, punctiform; marginal glands black, on lateral fimbriae and apical cilia. Petals bright yellow, veined or tinged red, 9–15 × c. 3.5–4.5 mm, 1.5–1.7 × sepals, oblanceolate, rounded; laminar glands pale or black, distal, few; marginal glands black, lateral, few and apical to subapical on cilia. Stamens (18–)30–40, ‘3’-fascicled, longest 7–11 mm, 0.7 × petals; anther gland amber. Ovary c. 2.5 × 1.5 mm, narrowly ovoid-ellipsoid; styles 3, c. 1.7 × ovary, ascending. Capsule 5–8 × 3–4 mm, about equalling sepals, with 4–8 longitudinal vittae. Seeds mid brown, 1.5–2.2 mm; testa shallowly reticulate to reticulate-scalariform.
Woodland and subalpine humid habitats; 800–2200 m.
Turkey (west and central Anatolia).
Like H. aucheri, H. adenotrichum is related to H. thasium but along a separate line. Whereas in H. aucheri there is a trend toward reduction or elimination of the glandular fimbriae and glandular auricles partially developed in the bracts of H. thasium, in H. adenotrichum these are more strongly developed, as they are in its sister species, 4. H. orientale, and they occur on the leaves of both species. In contrast to H. orientale, however, H. adenotrichum appears to have a relict distribution, quite widespread but discontinuous.