| 1 | 
  Plants with a bulb; leaves channelled, quadrangular or almost cylindrical. | 
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  (2) | 
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  Plants usually with a rhizome, leaves flat, sometimes very narrow. | 
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  (5) | 
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  | 2 (1) | 
  Bulb tunics fibrous and netted, leaves 4-sided in section (subgenus Hermodactyloides). | 
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  1 Iris reticulata | 
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  Bulb tunics papery to tough and leathery, leaves chanelled (Bulbs usually with thickened fleshy roots; standard much reduced in size); subgenus Scorpiris). | 
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  (3) | 
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  | 3 (2) | 
  Aerial stem much elongated already during flowering, with internodes clearly visible between narrow (3-8 mm broad) leaves. | 
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  2 Iris aitchisonii | 
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  Aerial stem either very short or if elongated then internodes ± concealed by comparatively broad leaves. | 
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  (4) | 
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  | 4 (3) | 
  Storage roots long, not markedly swollen. Leaves 6-16 mm broad, with a distinct 0.5-1.0 mm broad white horny margin. Seeds without aril. | 
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  3 Iris stocksii | 
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  Storage roots short, swollen. Leaves 1-3 cm broad during flowering. Seeds arillate. | 
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  4 Iris platyptera | 
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  | 5 (1) | 
  Plant with tiny rhizomes and markedly swollen tuber-like as well as fibrous roots (Subgenus Nepalensis). Standard narrowly lanceolate, bent outwards and downwards like fall. | 
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  5 Iris decora | 
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  Plant with well developed rhizomes, sometimes slender and stolon-like; roots not swollen and tuber-like (except in section Hexapogon, subgenus Iris). Standard erect. | 
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  (6) | 
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  | 6 (5) | 
  Falls with a distinct beard of fairly long hairs (Subgenus Iris). | 
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  (7) | 
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  Falls without an obvious beard but may have coxcomb-like crest, or rarely a fine pubescence of very short unicellular papillae on the haft (Subgenus Limniris). | 
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  (11) | 
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  | 7 (6) | 
  Rhizomes stout, peduncle (aerial stem) unbranched or branched. Falls bearded, hairs on falls multicellular. Seeds non-arillate. | 
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  (8) | 
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  Rhizomes compact, non-stoloniferous or very short and knobby, hairs on falls unicellular. Seeds arillate. | 
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  (9) | 
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  | 8 (7) | 
  Bracts green, only a narrow margin scarious, outer one 7-11 cm long. Flowers white or pale lilac-blue. | 
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  6 Iris kashmiriana | 
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  Bracts scarious at least in the upper half, outer one up to 5 cm long. Flowers usually violet, many colour forms present. | 
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  7 Iris germanica | 
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  | 9 (7) | 
  Rhizomes very short or knobbly with long straight fleshy roots. Beard present on falls till middle of blade and standards sparsely bearded near base. | 
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  8 Iris falcifolia | 
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  Rhizomes compact. Beard present only on falls. | 
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  (10) | 
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  | 10 (9) | 
  Flowers on short (5-12 cm) peduncle (aerial stem); hypanthial tube only 2-3 cm long. Flower colour variable but usually lilac, purple or bluish with darker mottling and albino. | 
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  9 Iris hookeriana | 
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  Flowers ± without peduncle (aerial stem) but are carried on long hypanthium tube c. 5.0-7.5 cm long. Flower colour lilac-purple mottled and blotched darker as if infected with virus. | 
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  10 Iris kemaonensis | 
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  | 11 (6) | 
  Crest on falls of flowers absent. | 
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  (12) | 
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  Prominent cockscomb-like crest present on the falls of flowers. | 
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  11 Iris milesii | 
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  | 12 (11) | 
  Capsule with 6 ribs running longitudinally, 2 ribs at each of the 3 corners (rather than equally spaced around the capsule. Seeds with a loose papery coat. | 
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  (13) | 
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  Capsule not as above. | 
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  (16) | 
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  | 13 (12) | 
  Flowers deep golden yellow; blade of fall longer than haft. | 
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  12 Iris crocea | 
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  Flowers not deep golden yellow, blade of fall equal to or shorter than haft. | 
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  (14) | 
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  | 14 (13) | 
  Flowers 4-6 cm in diameter, pale blue varying to greenish lilac; falls 3.5-4.0 cm long, haft narrow, twice as long as blade. | 
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  13b subsp. sogdiana | 
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  Flowers >= 6 cm in diameter; white, dingy white yellow or grey purple, sometimes golden yellow or bright deep blue or violet blue. | 
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  (15) | 
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  | 15 (14) | 
  Flowers up to 15 cm in diameter; bright deep blue or violet blue with median yellow stripe; haft equal to or longer than blade. | 
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  13c subsp. notha | 
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  Flowers (6)- 7-8 (-10) cm in diameter, white, dingy white-yellow or grey purple, sometimes golden yellow; haft longer than blade | 
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  13a subsp. halophila | 
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  | 16 (12) | 
  Hypanthial tube only 2-3 mm long, so that falls and standards appear almost free. Seeds shiny, smooth, not wrinkled (Series Ensatae). | 
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  14 Iris lactea | 
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  Hypanthial tube 4-15 cm long. Seeds wrinkled. | 
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  (17) | 
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  | 17 (16) | 
  Peduncle (flowering stem) well developed at flowering time. Hypanthial tube 4-6 (-12) cm long. | 
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  15 Iris songarica | 
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  Peduncle (flowering stem) obsolescent at flowering time. Hypanthial tube 10-15 cm long. | 
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  16 Iris loczyi |