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Information Panels : Irises - Classification

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Author: Mgr. Milan Blažek

The Genus Iris


Iris is a typical genus of Iridaceae family. Its relatives, from generally known plants, are Gladiolus or Sword Lily (Gladiolus) and Crocus (Crocus). They belong to very rare plants of native Czech flora, but they are also genera of the most significant garden plants.

There are about 500 wild species of irises, but hundreds of thousands of cultivars. Only a smaller fraction has permanent value, most of them abolish in a time. Unfortunately, some significant hybrids, which don’t have much commercial attraction, abolish sometimes, too.

Irises come originally from northern hemisphere, but they are significant garden plant worldwide. Ecological conditions suitable for them are very diverse. They can be water side or marshy plants as well as right for extremely xerotherm locations. Some species are fixed to subtropical climate, but most of them are satisfied in temperate one. Where they prosper, irises belong to elementary garden plants of northern and southern hemisphere.



Iris Groups Characteristics and Their Representation in Collections.


For cultivation in local conditions, there are several iris groups, which are not closely relative. (Plants within each of them can hybridize, not likely in-between them.)

1. Bearded Irises
Irises have mostly sturdy and softer rhizomes and thick, bushy "beards" on each of the falls (lower petals) of the blossoms. They are called Iris barbata in Europe, or Bearded Irises as horticulture term or in English literature.

2. Apogon Group of Irises
They have tougher rhizomes and flowers without beard. That’s why they are called Beardless Irises in English, but Apogon in European garden literature.

They are divided into three smaller groups:
    2a. Siberian Irises – coming from Siberian Iris (Iris sibirica)
    2b. Spuria Irises – close to Seashore Iris (Iris spuria)
    2c. Japanese Irises – derived from Japanese Iris (Iris kaempferi)

3. Bulbous Irises

Sometimes they are treated as individual genera: Iridodictyum, Xiphium a Juno.

Irises in Pruhonice

Iris collection has its origins in assortment of Dendrological Society in twenties of the last century. Irises of all main groups were included in it although not in big numbers. Former assortments were used for horticulture purposes, but collection in Chotobuz Botanic Garden focuses on botanical inter-connections and genetic development leading to today’s modern irises. It preserves not only plants kept in previous Pruhonice or Czechoslovak collections, but also carefully selected garden irises of worldwide significance (historical or modern). Original priority was to intercept all significant irises grown in Czechoslovakia in the past, which major parts were lost from the culture in last few decades. Another important task, more important
from an international perspective, is to show genetic resources leading to these iris cultivars. Also to show plants, which weren’t grown here in the past, but which belong to the world cultural heritage. Irises collection of this structure and volume is not to be found anywhere else then in Pruhonice. Individual groups within the collection show gradual process from wild species and its natural variability or variability increased by breeding. Development in breeding follows next to today’s cultivars. Iris barbata collection is the most complete and also largest.



Plantings of Irises

Botanic garden and the collections were founded in 1963 under Czechoslovak Academy of Sciences. Fundamental part has been gathered before that from private and commercial sources, locally and from abroad. In the fifties of 20th century older cultivars from commercial growers were obtained and since 1957 systematic receiving for abroad started. This base was later used for wide exchanging of material with growers. The collection was from its beginning organized in chronological order according to dates of origins. Plantings were continually placed into exposition or production section of the garden. Irises are plants, which need transplanting once in time, a new position is the best. First large-scale display was open to public in 1974 when International Symposium of Genus Iris took place in the garden. The basic assortment (complete collection of genus Iris) is planted in a field culture in production section today and it is not open to the general public. It is accessible only with permission from garden staff. A representative selection is arranged into display in the exposition section of the garden called rosarium (a rose collection is places here, too). This part of the botanic garden was originally inspired by design from architect prof. Ivar Otruba.


Assortment of Bearded Irises in the Exposition Garden


This overview relies to the last transplanting in 2009

A. Wild species and ancient cultural forms of unknown origin: 184


1. Miniatures, mostly early bloomers (in a size from I. pumila to I. aphylla) - 55 items
2. Taller to tall, early to late blooming iris species, hybrids and ancient cultural forms – 129 items: 72 diploid plants are divided into three categories: selected clones I. pallida and I variegata – 34 items; different hybrids coming from these species – 21 items; other diploid species and inter-species hybrids – 17 items.

3. I. germanica and related – 67 items:
I. germanica itself – 23 items; plants similar to it but mostly tetraploid – 44 items.


B. Cultivars with known origin: 1268


1. Dwarf irises (15 to 40cm tall): 206 items

2. Medium irises (40 to 70cm tall): 184 items

    a. intermedia group – 154  
    b. miniature tall bearded – 12   
    c. border bearded – 18
3. Tall irises (70 to 110cm tall): 878 items

Display of Czech Breeding

Separate part of tall bearded irises is dedicated to Czech breeding. It is a systematic display in chronological order including 60 items starting in 1966 when first Czechoslovak hybrid of garden irises was selected. Since the fifties, when breeding started, Czech irises won several European awards, and the qualities of Czech and Slovak hybrids are highly valuated overseas today.


Other Iris Groups

Since 2010, there is a new display bed with siberian irises showing 175 items. They are selected seedling of I.sibirica, cultivars in chronological order (124 items) and inter-species hybrids.

There are Japanese irises, too. This exposition was planted in the fall of 2012. It shows about 100 species, hybrids and cultivars and further development is worked on.

Bulbous irises are also included in the collections, but the blooming season is out of garden opening schedule.



Translation: Marketa Machackova