Flora of Khosrov Reserve is rich in rare, endangered and endemic plan species. Over 80 species are listed in the Red Data Book of Armenia: Plants (1990). Flora of vascular plants numbers 1849 species from 588 genera and 107 families. Endemic plants are 24.
Clayey and rubbly soils of the foothills at lower elevations provide a substrate for growing of semi-desert communities dominated by wormwood (Artemisia fragrans) and saltwort (Salsola ericoides, S. dendroides) accompanied with Halanthium rarifolium, Eurotia ceratoides, Xeranthemum squarrosum and others. Halanthium rarifolium and spring ephemers are the principal species on gypsum clays. Communities of caper (Capparis spinosa), thyme (Thymus kotschyanus) and some other plants are also widespread. Phryganoid communities consisting of buckthorn (Rhamnus pallasii), almond tree (Amygdalus fenzliana) and other plants grow on stony grounds.
In elevations 1400-2200 m where arid grasslands, sparse forests and oakeries are distributed, dominating plants are junipers (Juniperus polycarpos, J. oblonga, J. depressa), maple (Acer ibericum), almond, buckthorn and others.
Flora of elevations 2200-2800 m covered by subalpine and alpine meadows includes common grasses growing also in other landscapes, plus Phleum protense, Hordeum bulbosum and others.