Family: Rosaceae Juss.
Sorbus gemella
Distribution: Endemic taxon of the Czech Republic described as a stenoendemit of unnamed hill east of Konětopy village in the Džbán area (north-west Bohemia). Then found in eight other localities around the villages of Hřivnice, Třeskonice, Hořany, Markvarec, Břínkov, Solopysky, Ročov and Dolní Ročov.
Habitat: This light-demanding species occurs in open woods and their margins. Found in basifilous open oak woods, ravine forest, peri-alpidic basiphilous pine forest, xerofilous shrubs, dry forest margins, and also pine plantations (Pinus sylvestris or Pinus nigra).
Description: 3–10 m high deciduous tree, rarely bush. Lobed leaves have a broadly cuneate bases and are slightly yellowish tomentose on the underside. Flowers have a turbinate hypantium and the white petals, and are arranged to a corymb. Stamens partially connate, anthers yellow, sepals 1,8–2,6 mm long. It flowers in May. Ripe fruits are orange, glossy and have a densely dotted surface.
Mismatch: For the determination of rowans it is necessary to use leaves from fertile brachyblasts originating neither from extremly exposed nor shaded part of the tree. The most similar taxon from the Džbán area – S. danubialis differs in the shape of leaf and has red fruit and free stamens. Morphologically the most similar species is Sorbus rhodantera which occurs only on Chlumská hora by Manětín in the Plzeň (Pilsen) area.
Endangering and Protection: S. gemella is a critically endangered plant (CR). The future of the species depends mostly on forest management. Another endangering factor is also the high number of game in the forests.
Note: This apomictic hybridogenous species belongs to the group of S. latifolia agg. along with other rowans originated from crossing between S. torminalis and members of the S. aria agg. The shape of the leaf is inheritep from the first parent, the tomentose leaf underside from the second.
Sorbus gemellaSorbus gemella
Sorbus gemella
Sorbus gemella
Photos: 3. 7. 2007 (Czechia, Dolní Ročov – Alena Jírová), 19. 9. 2004 (Czechia, Konětopy – Martin Lepší), 14. 10. 2007 (Czechia, Markvarec and Kočovská stráň – Vladimír Hans).

Literature:
Lepší M., Kaplan Z. & Lepší P. (2008): Sorbus gemella. – In: Ondráček Č. (Ed.): Floristický kurz ČBS Louny 2007. – Severočeskou přírodou, in prep.