Iris 

(ii' riss)

Common name: Iris

Family: Iridaceae, Iris

Height x width: 4"-48" depending on species

Growth rate: moderate to fast

Foliage: narrow, generally linear to lanceolate, sheathing base, parallel-veined, mostly basal in fans or from bulb center

Flowers: generally 1-6 on stalks above leaves; 3 outer flower segments (falls) often drooping downwards (reflexed), sometimes with a central "beard" of colored hairs or ridge, often with a patch of different color (signal); 3 inner flower segments (standards) often upright and narrow in some species; standards and falls may be different colors, most colors available (photo courtesy Todd Weinmann, ext.nodak.edu)

Hardiness: zones 3 to 6 - 8 to 9

Soil: well-drained to wet depending on species

Light: sun

Pests and problems: bacterial soft rot and leaf spot, botrytis blight, fungal leaf spots and rusts, rhizome and crown rots, blue mold, mosaic virus, aphids, iris borer, thrips, nematodes, grubs

Landscape habit, uses: border in mass or in groups alone, some species in wet areas, cutting

Other interest: many of hybrid origin, species native to northern temperate regions; the name is for the Greek goddess Iris who supposedly walked between heaven and earth on a rainbow, and wherever she stepped on earth there arose flowers with as many colors as the rainbow (refering to the many colors available in this genus); irises have been used as emblems as early as the 6th century and by kings and countries (especially France) and provinces (such as Quebec in Canada) since; irises can be found in most styles of gardens in most countries.

Other culture: tall cultivars may need staking; divide or plants generally during dormant summer period after bloom; for bearded types with swollen rhizomes, plant with top at and parallel to soil surface; avoid heavy nitrogen fertility for best bloom; cut off diseased leaves late in season.

Propagation: divide rhizomatous types with sharp knife or spade, or pull apart such as with garden forks, usually just after bloom; cut foliage back to about 6" above crown

Species:

There are over 300 species of iris, of which the ones below are most common. Species can be differentiated by type of roots, most being rhizomes but some being bulbs (danfordiae, reticulata, 'Xiphium' hybrids). Species can also be differentiated as bearded (Pogon iris) with the central stripe of hairs on the falls (Bearded hybrids, pallida), crested (Lophiris) with the raised central ridge on the falls (cristata, tectorum) and those with neither beard nor crest (Limniris) which includes most other species. This genus is one of the most complex and often confusing taxonomically, being divided into sub-genera, then into sections, sub-sections and groups or series with 5-25 species in each group or section, and each species with many cultivars. Colors below are ones commonly found in the speices, with variation with cultivars. Soil preference is either damp (laevigata, versicolor, virginica prefer wet) or normal being well-drained.
 
 
 
Species height flowers bloom zones soil native
Bearded hybrids 8-36" various summer 3-10 normal various
chrysographes 20-24" dark red summer 4-9 damp Asia
cristata 6-8" lavender spring 3-8 normal U.S.
danfordiae 2-4" yellow early spr. 5-9 dry Turkey
ensata 24-30" various summer 4-9 normal Asia
foetidissima 18-24" lilac summer 6-9 normal Europe
laevigata 18-24" blue, purple summer 4-9 damp E. Asia
Louisana hybrids 36-48" various summer 4-9 damp SE U.S.
pallida 24-36" violet summer 4-9 normal N. Italy
prismatica 10-12" blue early sum. 4-9 normal E. U.S.
pseudacorus 24-36" yellow early sum. 4-9 damp Europe
reticulata 2-4" violet early spr. 5-8 normal Turkey
setosa 6-36" purple early sum. 4-9 normal NE U.S., Asia
sibirica 24-36" blue early sum. 3-9 damp Europe, Russia
tectorum 12-18" lilac summer 4-8 normal Asia
versicolor 6-30" purple summer 4-9 damp E. U.S.
virginica 6-30" blue summer 4-9 damp E. U.S.

(Siberian iris and tall bearded photos courtesy Todd Weinmann, ext.nodak.edu; others unless noted courtesy Missouri Botanical garden plantfinder)


Cultivars:

The following are only a few representative of the most available in the U.S. Bearded hybrids have been divided by height into Dwarf Bearded (DB) 4-10" tall, Standard Dwarf Bearded (SDB) 10-15", Intermediate Bearded (IB) 15-28", and Tall Bearded (TB) over 28". Dutch iris are hybrids generally of xiphium and tingitana.
 
 
Cultivars species,group flowers
'Activity' ensata soft blue, purple veins
var. alba cristata white, yellow crests
var. alba tectorum white, yellow crest on falls
'Angel Wings' Dutch white
'Ann Dasch' sibirica violet blue, pale blue mottle
'Anna Belle Babson' TB deep pink, tangerine beard, large
'Baby Blessed' SDB lime yellow
'Banbury Ruffles' DB purple
'Bastardii' pseudacorus creamy yellow
'Beverly Sills' TB peach, Dykes award winner
'Brown Lasso' IB yellow gold standards, orchid falls
'Butter and Sugar' sibirica butter yellow, white standards
'Caesar's Brother' sibirica velvety violet
'Cantab' reticulata pale blue, violet on falls
'Carrot Curls' SDB orange, crinkled edges
'Cherry Garden' SDB red purple standards, bluish beard
'Claret Cup' versicolor burgundy red, white and yellow falls
'Cry of Rejoice' ensata purple, yellow centers
'Dancing Nanou' sibirica violet blue, ruffled purple falls
'Dewful' sibirica blue, paler styles
'Dover Beach' TB blue
'Dreaming Spires' sibirica lavender and royal purple
'Dreaming Yellow' sibirica white, creamy white flaring falls
'Ego' sibirica reddish purple
'Eric the Red' sibirica red violet
'Ewen' sibirica violet red
'Flight of Butterflies' sibirica blue, small
'Flore-plena' pseudacorus yellow, double
'Forrest McCord' sibirica velvet violet blue, gold and white blaze
'Fourfold White' sibirica white, yellow at base of falls
'Gallant Moment' TB bronze-red
'Going My Way' TB purple, orange beard, ruffled
'Golden Harvest' Dutch dark yellow
'Gypsy Caravan' TB gold, maroon
'Halcyon Seas' sibirica dark 3-tone blue purple
'Harmony' reticulata royal blue, yellow and white blotched falls
'Harpswell Happiness' sibirica creamy white
'Henry's White' ensata white, yellow striped falls
'Illini Charm' sibirica lilac, white, violet veins
'Imperator' Dutch medium dark blue
'Joyce' reticulata sky blue, white blotched falls
'Joyce Terry' TB yellow, white, white falls
'Laced Cotton' TB white, lacy, large
'Lady Friend' TB garnet rose
'Lady Vanessa' sibirica wine red, ruffled
'Lavender Bounty' sibirica lavender falls, lighter standards, early
'Lemon Mist' TB light yellow, ruffled, flaring falls
'Limeheart' sibirica creamy white to light yellow
'Modern Classic' TB white, violet veins, pale yellow beard
'Mulled Wine' TB raspberry burgundy, lacy
'Mystique' TB violet purple, blue beard slightly ruffled
'Navy Doll' DB light yellow, purple splotch
'Olympiad' TB light blue, lighter falls
'Orville Fay' sibirica blue, darker veins
'Pansy Purple' sibirica velvet violet
'Perry's Blue' sibirica sky blue
'Pink Bubbles' IB pink, deeper beard, flared, ruffled
'Pink Lady' ensata light pink, single, large
'Pippi-longstockings' SDB bright yellow, purple spots
'Pirate Prince'
sibirica
bluish purple
'Purple Gem' reticulata deep purple
'Purple Sensation' Dutch dark violet purple, yellow marked falls
'Rain Dnce' SDB clear blue
'Ritz' DB yellow standards, blue tint
'Royal Banner' ensata purple red, yellow blotch
'Royal Herald' sibirica dark purple
'Ruffled Ballet' TB light blue standards, darker falls, ruffled
'Ruffled Velvet' sibirica deep velvet purple
'Savoir Faire' sibirica cobalt violet, small yellow
'Shirley Pope' sibirica velvet red-purple, wide, white
'Silver Edge' sibirica purple, silver edges
'Sky Wings' sibirica purple pink
'Snow Maiden' SDB white, chartreuse veins
'Snow Queen' sibirica snow white
'Sparkling Rose' sibirica red violet
'Summer Storm' ensata deep purple, yellow marking
'Super Ego' sibirica light blue and lavender bicolor
'Supersimmon' TB bright persimmon orange
'Superstition' TB ebony black, black-blue beard, ruffled
'Tarheel Elf' SDB deep purple
'Tealwood' sibirica violet black, flat standards
'Tycoon' sibirica violet blue, large, drooping falls
'Variegata' ensata dark purple, white edged leaves
'Variegata' pseudacorus greenish-gold leaves early and late, yellow
'Vi Luihn' sibirica deep cobalt blue, pale yellow
'Watercolor' DB light yellow brown spot on falls
'White Swirl' sibirica white, yellow tint

 


©Authored by Dr. Leonard Perry, Professor, University of Vermont as part of PSS123 course.

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