Habitats, Plant Diversity, and Molecular Phylogeny of Endemic Relic Species Incarvillea semiretschenskia (Bignoniaceae)

<i>Incarvillea semiretschenskia</i> (B. Fedtsch.) Grierson is listed in the Red Data Book of Kazakhstan as a rare relic, narrowly endemic species of the Shu-Ile low mountains (Kazakhstan). The aim of this research was to advance our knowledge of the ecological conditions of its habitats, the floristic composition of plant communities, and molecular phylogeny, as well as to identify threats to the species' existence. The ecological conditions of <i>I. semiretschenskia</i> habitats are rocky slopes and intermountain valleys of the low mountains in the altitude range from 812 to 1075 m asl with light chestnut mountain soils of little development, having a light granulometric composition and containing insignificant amounts of organic matter. We revealed 164 species of vascular plants in the communities of <i>I. semiretschenskia</i>, including five endemics and five species from the Red Data Book of Kazakhstan. Anthropogenic factors associated with grazing, fires, and limestone mining were identified as leading to a decrease in the number and density of populations. New insights into the relationship and time of diversification in the genus <i>Incarvillea</i> are gained through the use of several accessions of <i>I. semiretschenskia</i> and <i>I. potaninii</i> Batalin in the phylogenetic study. Preliminary fingerprint analysis shows relatively high genetic variability within populations of <i>I. semiretschenskia</i>. This unique relic species has survived since the Miocene epoch and exists to this day only in the Shu-Ile low mountains. To preserve this rare species, measures are proposed to create plant micro-reserves to provide ex situ collections and ensure future in situ restoration efforts.