Crataegus chlorocarpa, commonly known as the Altai Mountain Thorn, is a deciduous shrub or small tree belonging to the rose family (Rosaceae). This species is characterized by its thorny branches and its attractive display of flowers and fruits, making it a notable component of its native ecosystems. The Altai Mountain Thorn typically grows to a height of 3 to 6 meters, forming a dense, often rounded crown. Its branches are armed with stout, sharp thorns, a common defense mechanism in many *Crataegus* species. The leaves are alternate, simple, and ovate to obovate, measuring approximately 2 to 5 centimeters in length. They are typically lobed and serrated along the margins, with a somewhat leathery texture. In autumn, the foliage often develops attractive yellow to reddish-brown hues before abscission. The plant produces clusters of white, fragrant flowers in late spring or early summer. These flowers, typical of hawthorns, have five petals and numerous stamens. Following successful pollination, the flowers develop into small, berry-like fruits known as pomes. The pomes of *Crataegus chlorocarpa* are typically globose to ovoid, measuring about 0.8 to 1.2 centimeters in diameter. Their color is a distinctive green to yellowish-green, which gives rise to the specific epithet "chlorocarpa" (meaning green fruit). These fruits persist into winter, providing a food source for wildlife. The bark is generally gray and somewhat fissured on older stems. *Crataegus chlorocarpa* is native to the mountainous regions of Central Asia, specifically found in the Altai Mountains and surrounding areas, extending into parts of Siberia and northwestern China. It thrives in a variety of habitats, often growing in open woodlands, along stream banks, on rocky slopes, and in shrubland formations. It prefers well-drained soils and can tolerate a range of soil types, from sandy to loamy. While it is adapted to cold climates and can withstand significant frost, it benefits from adequate sunlight for optimal growth and flowering. Cultivation requirements generally include full sun to partial shade and protection from extreme winds. The ecological role of the Altai Mountain Thorn is significant within its native range. Its fruits are an important food source for various bird species and small mammals, particularly during the autumn and winter months. The dense thorny structure provides shelter and nesting sites for birds. While not widely cultivated for ornamental purposes outside its native region, its hardiness and attractive features suggest potential for landscape use in suitable climates. Information regarding specific medicinal, culinary, or economic uses of *Crataegus chlorocarpa* is not extensively documented in widely accessible scientific literature, distinguishing it from some other more widely studied hawthorn species. An interesting characteristic of *Crataegus chlorocarpa* is its adaptation to high-altitude environments, where it can endure harsh winter conditions. The persistent green fruits, even when ripe, are a distinctive feature that aids in its identification and highlights its unique evolutionary path within the diverse *Crataegus* genus.