Authors: RNDr. Pavel Sekerka, Ing. Markéta Macháčková, Mgr. Milan Blažek
Bulbous irises are peculiar a group of irises in terms of botany and gardening. First descripttion of genus Juno by Leopold Trattinnick is dated back to the beginning of 19th century. But the most merit in bulb-iris taxonomy have Soviet botanists, especially G. I. Rodionenko. Today, all three separate genera of bulbous irises (Juno, Xiphium, lridodictyum) are again considered as subgenera of a large genus Iris.
Irises of Subgenus Scorpiris (Juno)
They range from subtle to large (higher than 50cm) plants. Bulbs have noticeable, long and thick roots, pulp is smooth and leaves are quite broad and folded in a V shape. Larger species resemble of corn. These irises grow in Mediterranean, Near East and central Asia. There are 56 species described. Flowers season is spring to beginning of summer.
English irises – their ancestor is Iris latifolia (syn.: I. xiphioides) from mountain meadows of Pyrenees. Foliage appears in spring, flowers are violet, blue or white with yellow basal stigma, never completely yellow. They can reach 1m, that’s why they are very suitable as cut flowers. Spanish irises – come from Iris xiphium. Original species grows in West Mediterranean, Corsica and South Italy. Foliage appears in fall and flowers are in colors of blue, violet, white and yellow. They have a long tradition as garden plant, e.g. Phillip Miller in 1732 talked about 16 varieties. They are mostly cut flower, but in this region they aren’t frost hardy. Dutch irises – are a substitution for Spanish ones since the fifties. They are hybrids of Iris xiphium, I. tingitana a I. latifolia. The breeding has been done mostly by Hoog brothers working for van Tubergen Company. Plants are more tolerant to frost and grown mostly as cut flowers 40 – 60cm tall. When growing outdoors, they flower in June and last quite long, but foliage appears the fall before and it can get some frost damage. Winter cover of conifer branches helps.
Irises of Subgenus Hermodactyloides (Iridodictyum)
These subtle plants are10cm tall when flower. Smaller bulbs are covered with reticulate residue of old leaves. Foliage has square profile and it appears in spring when flower. There are about 10 species from Mediterranean and Central Asia described. These irises are favorite garden bulbs. The most frequent are Reticulated Iris (lris reticulata) coming from Turkey and Caucasus, Danford Iris (lris danfordiae) from East Turkey and other Iris histrioides from North of Turkey. They have created many garden cultivars which are different in flower color. Very attractive are also inter-species hybrids like ‘Katherine Hodgkin´ which is a natural hybrid between I. histrioides and I. winogradowii. Seeds from spontaneous pollination were sown in 1955 by E. B. Anderson to get first flowers in 1960. Today it is the most often reticulated iris for its attractive look. Cultivar ‘Lady Beatrice Stanley’ has same parentage. Other inter-species hybrids are varieties ´Harmony´ and ´George´ from Iris histrioides x Iris reticulata. All there irises flower in spring, in local conditions it is from end of February to beginning of April.