Study of the distribution of Linaria cretacea in Kazakhstan and neighboring countries: data from an electronic herbarium

Abstract

Linaria cretacea Fisch. ex Spreng., commonly known as chalk toadflax, is a rare alciphilous species in the family Plantaginaceae, listed in the Red Data Books of Kazakhstan and Ukraine. Here, we present a synthesized overview of its distribution derived from digitized herbarium records (Kazakhstan, Russia, Ukraine) and recent field surveys in the Aktobe Region, alongside an ecological characterization of its chalk‐derived habitats. The species’ range is highly disjunct, spanning eastern Ukraine, the southern European part of Russia (Don River basin), and the far northwestern corner of Kazakhstan. Most populations occur on exposed, rubbly chalk slopes—so‐called “chalk mountains.” We analyzed specimen data and observations by region and year, producing summary maps and distribution tables. In Kazakhstan, only a handful of isolated populations in the Aktobe Region have been confirmed by up‐to‐date collections and in situ observations. Key habitat features include calcium‐rich substrates, continental steppe climate, and a specialized chalk flora. We discuss the low population densities and high vulnerability of L. cretacea owing to its narrow ecological niche and anthropogenic threats—chalk quarrying, livestock grazing, and successional overgrowth. The current conservation status across its range is reviewed, and recommendations for population monitoring and protection are offered. We conclude by emphasizing the scientific importance of chalk ecosystems and the urgent need to safeguard these refugia for relict plant species.