Verbascum tzar-borisii
Verbascum tzar-borisii (Stoj.) Stef.-Gat.
Scrophulariaceae – Figwort family
Conservation status. Critically Endangered [CR B1ab(iii)+2ab(iii)]. BDA. Bulgarian endemic.
Morphology and biology. Perennial plant. Flowering stems erect, 40–70 cm, white-tomentose. Rosette leaves wide-lanceolate, 7–15 × 2.5–4 cm, serrate, white-tomentose, sometimes floccose on the upper surface. Cauline leaves smaller. Inflorescence paniculate, flowers in groups of 2–3. Corolla 20–25 mm in diameter, pale yellow, outer surface with dense cover of branched hairs. Stamens 5, filaments yellowish, with long white papillae, anthers pale yellow, reniform. Fruit a 4–5 mm long ovoid capsule. Fl. V–VI, fr. VIII–IX. Insect pollination. Reproduction by seeds.
Habitats and populations. Grows in a specific habitat: very open grassland communities on clayey marls slopes with stony outcrops. The species has low competitive ability, grows on very poor soils, in dry sunny places. Locally, 4 subpopulations are known, area of occupancy is less than 1.5 km2. Subpopulations on the hills near Devnya town numbers respectively about 700–850 and 150(170) individuals, the two subpopulations on Venchanski Dyuz hill, approx. 1000 individuals. The very low percentage of flowering individuals is typical, 1–5%.
Distribution in Bulgaria. Black Sea coast (Beloslav town – possibly extinct), NE Bulgaria (Sivri Tepe and a neighboring hill near Devnya town, Venchanski Dyuz hill near Venchan village); up to 300 m alt.
General distribution. Bulgaria.
Threats. Limited distribution and extreme conditions of the habitat; attempts for afforestation of the hills.
Conservation measures taken. Protected species by the Biodiversity Act. The locality on Venchanski Dyuz hill is in a protected area, which is part of a site of the European ecological network Natura 2000 in Bulgaria. An Action plan for conservation of the species is in a process of elaboration.
Conservation measures needed. Studies on the population status, biology and ecology of the species; declaring the Sivri Tepe locality a protected area; preservation of seeds in the National Seed Genebank in Bulgaria.
References. Stojanoff 1928; Stefanova-Gateva 1995.
Author: Antoaneta Petrova
