Iris Classifications

The irises most often used
as garden plants fall into three main groups:
Bearded Irises,
Aril
Irises and
Beardless Irises
Each
group has its unique qualities, and a collection including
representatives from each group will be varied indeed. For cultural information on the irises described below follow the "About Irises" links in the menu on the left.
Bearded Irises
Bearded Iris are identified
by thick, bushy "beards" on each of the falls (lower petals)
of the blossoms. Originally, most of these were native to central and
southern Europe. The American Iris Society has divided the bearded
irises into six groups for garden judging awards.
1. Miniature Dwarf
Bearded (MDB) -- the tiniest of bearded irises, with height of up to 20 cm (8 inches). They are also the earliest to
bloom. They are most effective in rock gardens or planted in drifts
where they make a "carpet of color."
2. Standard Dwarf Bearded
(SDB) -- some of the most useful garden plants, ranging in height
from 20 cm (8 inches) to 41 cm (16 inches). They begin their bloom as
the MDBs are ending, still quite early in the iris season. They are best
displayed in clumps where they give the effect of a "cushion"
of individual blooms. The colors are nearly unlimited since the SDBs
show all the different "spot patterns" of the miniatures, as
well as the plicatas and pinks seen in the TBs.
3. Intermediate Bearded
(IB) -- stand from 41 cm (16 inches) to 70 cm (27 1/2 inches) high, with
their bloom season overlapping the SBDs and the TBs. Although the IBs
show their dwarf ancestry in early bloom season and very interesting
color patterns, they are large enough that their individual stalks may
be nicely branched, forming an elegant bouquet. Some varieties are
nicest in clumps, where they present a large amount of color (like the
SDBs), while others are showiest in specimen plantings, where the stalks
and individual blooms may be seen to best advantage.
4. Border Bearded (BB) -- essentially small versions of the TBs in the same height range and
bloom size as the intermediates, but blooming with the tall beardeds.
Good BBs have round, ruffled petals that complement their small size.
5. Miniature Tall Bearded
(MTB) -- this class is
distinguished by daintiness and delicacy. Height from 41 cm (16 inches)
to 70 cm (27 1/2 inches). The blooms are smaller than on
a BB and the stems are thin and wiry. An MTB clump looks like a cloud of
butterflies. They are often called "Table Irises" because they
are so well suited for arrangements.
6. Tall Bearded (TB) -- have stalks with a height of 70 cm (27 1/2 inches) and above, with branching and many buds. Each stalk,
in itself, makes a stately arrangement in the garden or in a vase. In
addition to a wide variety of colors and patterns, the TBs display other
qualities (such as ruffling and lacing) more frequently than do the
other classes
Even if you grow nothing but
bearded irises, you can enjoy a remarkable range of color and a bloom
season extending for months. Some bearded irises are "rebloomers",
blooming again in the summer, fall or winter. Additional water and
fertilizer applied during the summer months encourages them to bloom
again. There are now reliable attractive rebloomers available which will
perform in all but the coldest climates.
Incidentally, the word
"median" refers to all the bearded irises except the miniature
dwarfs and the tall beardeds; that is to say the SDBs, IBs, BBs and the
MTBs. Strictly speaking, the word "dwarf" means only the MDBs.
Aril Irises
Two very different types of
irises are grouped together under the term "aril". These are
the oncocyclus and regelia irises of the Near East. Although they have
beards, they are not classified with the bearded irises because they are
so different. Actually, their beards are rather sparse, being long and
straggly on the regelias, and nothing more than a wide "fuzzy"
patch on the oncocyclus. The arils show dark signal spots below the
beards with much veining and speckling, in an unbelievable range of
colors. Unfortunately, the arils are difficult to grow in all but the
warmest and driest regions of the United States.
However, in this century,
hybrids were produced from crossing the arils with the more common
bearded irises. These are called "arilbreds" (AB), and are
usually very easy to grow and still display the spectacular features of
the arils. Most arilbreds are tall and have large blooms. They usually
bloom earlier than the TBs, with the SDBs and the IBs.
There are also small
arilbreds, produced from crossing arils or arilbreds with dwarfs or
medians. They are variously called "arilbred-medians",
"aril-medians" or "aril-meds".
Beardless Irises
Beardless Irises are mostly
native to Asia. The first four types are commonly grown in gardens, and
they all bloom after the TBs, extending the iris season even longer. The
fifth type, the Pacific Coast Native, blooms before the TBs and is
native to the western regions of the United States.
1. Spurias (SPU) are
tall (2 to 5 feet in height) and elegant, and have very attractive
foliage. The shape of the bloom often suggests orchids and the colors
range from white and yellow through blue, wine and brown, often with
bright yellow signals.
2. Siberians (SIB) perform best with cooler conditions, regular moisture and a slightly
acid soil. The blooms can be blue, purple, red-violet or yellow with
newer cultivars in brown and orange shades, and can have a variety of
forms from upright to flat and round. They are most attractive in
established clumps that develop a bouquet effect and grow to a height of
2 to 4 feet., although some dwarf varieties are also available. Their
grass-like foliage after bloom is one of their attractive garden
features. They tend to bloom slightly later than the TBs.
3. Japanese (JI) require
a slightly acid soil and present some of the most spectacular flowers of
all the irises. Blooms are usually huge, ruffled and flat in form; some
are marbled with gray or white. They bloom about a month after the TBs.
Japanese hybridizers have worked with them for over 500 years.
4. Louisianas (LA) are native to the American Gulf Coast; they require soil that is
somewhat acid and wet in the spring. The blooms are usually very wide
petaled and open, showing brightly colored style-arms and sharp
signal-crests.
5. Pacific Coast Natives
(PCN), or Californicae (CA), are not widely grown as they are
intolerant of the climatic conditions of all but the far western area of
the country. Where they can become established, they grow most
attractively with graceful and dainty flowers held one to two feet high,
in most colors and patterns.
6. Species often
enhance gardens with their delicate beauty. I. confusa (Evansia)
requires conditions similar to azaleas in a frost free climate. I.
missouriensis enjoys wet springs and dry summers.
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