Psammiris, Spach, 1846

Alexeeva, Nina B., 2018, A taxonomic revision of Iris section Psammiris (Iridaceae) in Russia, Phytotaxa 340 (3), pp. 201-216 : 205

Key to the species of I. section Psammiris in Russia

1. Rhizome vertical, short, with a dense bundle of radial adventitious roots, never forming clumps, scapes up to 20–35 cm, seeds with aril 2.4 (± 0.2) long, 2.2 (± 0.1) mm wide (ser. 1. Vorobievia).................................................................................. 1. Iris vorobievii

- Rhizome horizontal, creeping or short-creeping, forming clumps with numerous thin-fibrous or membranous remains of old leaf sheaths, scapes up to 10–15(25) cm, seeds with aril 1.1 (± 0.3) long, 1.2 (± 0.4) mm wide.............................................................2

2. Rhizome thin, short-creeping, stoloniferous, plants up to 20(25) cm tall, flowering scape distinct, perianth tube shorter than blade (ser. 2. Humilis )..................................................................................................................................................................................3

- Rhizome poorly developed, short and small, plants 10–15 cm tall, flowering scape short, perianth tube longer than blade (ser. 3. Potaninia)...........................................................................................................................................................................................5

3. Stoloniform offshoots short, forming dense clumps, flowering scape 15 cm, spathes green, herbaceous or pergamaceous, not swollen................................................................................................................................................................................................4

- Stoloniform offshoots extended, forming loose clumps, flowering scape 20–25 cm, spathes herbaceous, green, swollen ................ ................................................................................................................................................................................... 2. Iris bloudowii

4. Spathes pergamaceous, scape base surrounded by brown fibrous remains of old leaves ............................................ 3. Iris humilis

- Spathes herbaceous, light-green, scape base surrounded by grey fibrous remains of old leaves........................ 4. Iris mandshurica

5. Rhizome covered with fibrous remains of old leaf sheaths................................................................................................................6

- Rhizome covered with membranous remains of old leaf sheaths ............................................................................. 5. Iris kamelinii

6. Old leaf sheaths hair-like, sometimes winding, flowers sulphur-yellow.................................................................... 6. Iris potaninii

- Old leaf sheaths coarsely fibred, erect, flowers light yellow ............................................................................... 7. Iris psammocola