Quercus species

Tashev, Alexander & Tsavkov, Evgeni, 2017, Validation of the name Quercus protoroburoides (Fagaceae), Phytotaxa 308 (2), pp. 232-238 : 236

Key to Quercus species belonging to section Robur in Bulgaria

1. Leaves uniformly sinuate-dentate, with more than 8 pairs straight and parallel lateral veins, intercalary veins absent....................2

- Leaves pinnatifid to deeply pinnatifid, with up to 4–8 pairs lateral veins, with intercalary veins.....................................................3

2. Ramules red-brown, glabrous, relatively thin, terminal buds up to 4 mm, fruits on relatively thin peduncle (up to 1, 5 mm); only in Strandzha Mt., from 0 to 500 m a.s.l., along rivers........................................................................................... Quercus hartwissiana

- Ramules light-brown, tomentose (at least on basis strongly tomentose), relatively thick, terminal buds bigger, 4–8 mm, fruits on relatively thick (up to 3 mm) peduncle; only in Rila Mt., at 1500–1750 m a.s.l., on dry, stony, very steep habitats .......................... .................................................................................................................................................................... Quercus protoroburoides

3. Leaves glabrous............................................................................................................................................................ Quercus robur

- Leaves greyish-puberulent beneath....................................................................................................................................................4

4. Leaves pubescent on the upper surface (with fasciculate-radiate) ......................................................................... Quercus mestensis

- Leaves glabrous on the upper surface ............................................................................................................ Quercus pedunculiflora