Key to subspecies of Psammogeton canescens (DC ex Boiss.) Vatke
1. Main axis elongate, lateral branches shorter than the main axis ———————————————————————————————————–P. canescens subsp. canescens
– Main axis and lateral branches arising from the base of axis ———————- 2
2. Branches slightly shorter, never overtopping the main axis; peduncle up to 3 cm long ————————–P. canescens subsp. buschirensis
– Branches always overtopping the main axis; peduncle up to 8 cm long —————————————————————————————————P. canescens subsp. cabulicus