Chionoloma undetermined

KEY TO IDENTIFICATION OF CHIONOLOMA SPECIES OCCURRING IN RUSSIA

1. Leaves acute at apices, often fragile, with sinuose upper leaf margins, or not fragile, with papillose-crenulate or weakly and distantly denticulate upper leaf margins; costa papillose on dorsal surface in distal leaf portion or smooth throughout ...................... .................................................... 1. C. tenuirostre View in CoL

— Leaves rounded, acuminate or cuspidate at apices, not fragile, with entire, papillose-crenulate or weakly and distantly denticulate upper leaf margins; costa smooth on dorsal surface from base to apex .... 2

2. Leaves oblong-lingulate, slightly widened distally, rounded at apices, often with constriction above base .................................................. 4. C. stenocarpum View in CoL

— Leaves linear-lanceolate or oblong-lanceolate, acute, acuminate or cuspidate at apex, not constricted above base ....................................................................... 3

3. Leaves often cuspidate and canaliculate at apex; leaf margins often faintly and distantly denticulate in upper and middle leaf portion; dorsal stereid band usually larger than ventral one; smooth basal cells do not form V-shaped pattern .. 2. C. cylindrotheca View in CoL

— Leaves acute or acuminate at apex, but never cuspidate; leaf margins entire; dorsal stereid band small- er or equal to ventral one; smooth basal cells form V-shaped pattern ....................... 3. C. orthodontum View in CoL