IRIARTEA 



IRIS 



1663 



Mart., but the plant is in cultivation under the former 

 name. 



exorrhiza, Mart. (7. Bungerothii, Hort.). Trunk 

 about 35 ft. tall, crowned by a congested cluster of 

 10-20 showy Ivs., each bearing 15-20 pairs of Ifts., the 

 latter about 20 in. long and 1J^ wide: spadices 1-4, 

 appearing between the Ivs.; fls. yellow: fr. olive-green, 

 reticulate. Trop. S. Amer. Doubtfully in cult, at 

 this time (1913) in Amer. N . TAYLOR.f 



IRIS (Greek, rainbow). Iridacese. Plates LYIII, 

 LIX. Showy and interesting flowers for outdoor 

 bloom, widely known and planted; perennials with rhi- 

 zomes or bulb-like root-stocks, mostly narrow long 

 leaves, and commonly erect habit; includes the blue flag 

 and fleur-de-lis. 



Herbs with linear or ensiform equitant Ivs. : st. simple 

 or branched : fls. of 6 segms., the 3 outer reflexed, and 

 the 3 inner usually smaller and erect, always narrowed 

 to a distinct claw, 1 to many in terminal heads, from 

 spathes which are formed of the upper bract-like Ivs.; 

 spathe stalked or sessile; style divided into 3 petal-like 

 branches, which are bifid or crested at the tip; stig- 

 matic surface immediately below the crests; ovary ses- 

 sile or pedicelled, within the spathe. Distinguished 

 from the other members of the tribe except Hermo- 

 dactylus and Moraea by the 2-winged style-branches, 

 from Hermodactylus by the 3-celled caps., and from 

 Moraea by the more or less connate perianth-segms. 

 For monographs of the genus, see Baker's Irideae, 1888, 

 Lynch, The Book of the Iris, 1904, and the fine mono- 

 graph of Dykes, The Genus Iris, 1913. The number of 

 species of Iris recognized by different monographers 

 ranges between 140 and 170. The synonomy includes 

 something over 700 names. The extensive synonomy 

 is an indication of the great variability and wide dis- 

 tribution of the genus. In general the irises are natives 

 of the North Temperate Zone, but the different sub- 

 genera differ much in their distribution. The distribu- 

 tion of some of the subgenera is coextensive with that 

 of the genus, while others are restricted to limited 

 regions. The subgenus Apogon is the largest and also 

 the most widely distributed section of the genus. Its 

 representatives are found throughout temperate N. 

 Amer., Eu., Asia and N. Afr. They extend from Alaska, 

 Labrador and Kamtchatka in the north to Fla., Algiers 

 and Honkong in the south. The members of the sub- 

 genus Pogoniris, which is the second largest and horti- 

 culturally the most important section, are found in 

 Cent, and S. Eu. and N. Afr. and thence eastward to 

 China and N. W. India. No members of this sub- 

 genus are indigenous to Amer. The small subgenus 

 Evansia comprises a few species of crested irises which, 

 with the exception of the two closely related American 

 forms, 7. cristata and 7. lacustris, occur only in Japan 

 and E. China. The American species differ widely 

 from the far eastern ones in the absence of an evident 

 stem. The subgenus Oncocyclus is a small section 

 whose members are restricted to a limited region in 

 Asia Minor, Syria, and Persia. Farther to the east, in 

 Turkestan, the Oncocyclus irises are replaced by the 

 members of the closely related subgenus, Regelia. In 

 N. India in the region to the south of the Karakoram 

 and Himalayan Mts. are found a few species constitu- 

 ting the subgenus Pseudoregelia, so named on account 

 of the affinity of its members to those of the subgenus 

 Regelia, The peculiar oriental subgenus Pardan- 

 thopsis contains only a single species, 7. dichotoma, 

 which is found in Manchuria and N. China. The 

 bulbous irises comprise three subgenera, Xiphium, 

 Juno, and Gynandriris. The subgenus Xiphium is some- 

 times divided into two sections, the Xiphiums proper, 

 which occur in Spain, Portugal, Sicily and N. Afr.; 

 and the reticulata irises, which are found in Asia 

 Minor, Transcaucasia and Turkestan. The Juno irises 

 occur in Spain, N. Afr., Asia Minor, Persia, and east- 



ward to India. The single species of the monotypic 

 subgenus Gynandriris is distributed from Portugal to 

 N. W. India. 



Something over 100 species of Iris, with innumerable 

 garden varieties, are offered by dealers in America. 

 Many of these, including the native species, are culti- 

 vated only to a slight extent, so that horticultural 

 interest centers chiefly around the groups described 

 below. 



1. German irises. Under this head may be grouped 

 the tall European pogonirises and the numerous 

 varieties and hybrids derived from them. Besides 

 7. germanica, which may be taken as the type of this 

 class, the principal species of the group are 7. aphylla, 

 7. variegata, I. florentina, I. pallida, I. Cengialti, 

 I. flavescens, I. plicata, I. Swertii, I. Kochii, I, lurida, 

 I. neglecta, I. sambucina, I. squalens and 7. hybrida. 

 Many of these which are usually recognized as species 

 are undoubtedly of garden origin. 7. germanica itself is 

 not certainly known to occur in a native state. 7. floren- 

 tina or 7. albicans is a common ornament in Moham- 

 medan cemeteries and was undoubtedly distributed 

 throughout the Mediterranean region by the Moham- 

 medans, who carried it everywhere with them as an 

 embellishment for graveyards. 7. Kochii, I. lurida, 

 I. neglecta, I sambucina and 7. squalens are probably 

 hybrids of which there are innumerable forms in this 

 group. 7. Swertii and 7. plicata are pale forms of 

 7. Cengialtii and 7. pallida, in which the color is absent 

 except along the margin of the segments. 7. hybrida 

 probably represents a similar derivative of 7. variegata 

 in which the yellow color is absent. Owing to their 

 diversity of origin, the varieties of this group have a 

 great diversity of color, ranging from pure white through 

 all shades of mauve and blue to dark purple. From 

 7. variegata and 7. flavescens the yellow-flowered varie- 

 ties and those whose flowers are variegated with yellow 

 were probably derived. The flowers of all the varie- 

 ties are large and handsome, often stately, exhibiting 

 beautiful variegation and shades of color. They are 

 borne on stout, erect, branched stalks much exceeding 

 the clumps of spreading leaves. All are hardy, and form 

 excellent border plants, flowering in May and June. 



2. Japanese irises. All the plants cultivated as 

 Japanese irises are referable to a single species, Iris 

 laevigata, more commonly known as 7. Kaempferi. The 

 type of the species has been so much broken that its 

 varieties constitute a distinct horticultural group, con- 

 taining perhaps as many or more named varieties than 

 the germanica group itself. So far as known, no 

 hybrids or other species enter into the make-up of 

 this class. The plants form strong clumps, attaining a 

 height of 2 to 3 feet, and bearing several flower-stems. 

 The leaves are slender, erect, growing almost parallel 

 to each other. In the wild type the inner segments are 

 erect and rather small. The cultivated forms fall into 

 two groups, the three-petaled forms in which the 

 inner segments have been nearly suppressed while the 

 outer segments constitute the showy part of the flower, 

 and the six-petaled forms in which all the segments are 

 large and spreading giving the flower the flat expanded 

 form characteristic of the group. The flowers range in 

 color from white through various shades of blue to 

 deep purple, with the segments variegated with darker 

 veins and streaks, or plain. All the varieties are hardy, 

 and thrive best in cool, moist situations. They begin 

 flowering in the latter part of June and continue 

 through July. 



3. The tall apogon irises. Besides the Japanese 

 irises, two other groups of apogon irises deserve men- 

 tion on account of their ornamental value. These are 

 the sibirica group and the spuria group. The species 

 of the sibirica group which are of horticultural interest 

 are 7. sibirica, I. sanguinea, I. Wilsonii, and 7. 

 Delavayi. The plants of this group are characterized by 

 long grass-like leaves growing in close tufts from which 



