Aril And Arilbred Irises

These are bearded iris species from the very dry areas of Israel and Turkey and include Oncocyclus and Regelia irises as well as Arilbreds - hybrids derived from crosses made between tall bearded irises and species in the above-mentioned groups. The name aril relates to the peculiarity of a small white aril or collar-like appendage attached to the seed. Arils are generally not easy to grow in temperate climates, they tend to be susceptible to rust and to rhizome soft rot. Without a regular spray program, it is easy to lose them. However, low rainfall is the key factor in growing them successfully.

Quite different from other bearded irises, the Arils have fine, insignificant leaves that lack luster and vigor, in contrast to the lush green leaves of the standard bearded irises. But the flowers are spectacular, with interesting color patterns and shapes. The blooms of the Oncocyclus and Regelia are quite different from other bearded irises: the standards are rounded, almost closed together and quite large compared to the falls that recurve inwards under the flower.

The colors of the Arils can be very pure and clear, or the flowers can have amazing contrasting blotches on them. When crossed with bearded irises, some of these characteristics are retained and, in others, fascinating colors, streaks and patterns may emerge.

The best known (and easiest to grow) Oncocyclus species is I. susiana, sometimes called the mourning iris for its somber colors. Originally from Syria, it has been cultivated for 400 years but has never been found in the wild. Flowers are large, towering over the foliage, and the colors unusual, with standards and falls of creamy gray background and heavy, close veining of dark purple-brown. The signal patch on the falls is rich velvety ruby-black and the beard a deep purple-bronze.

Characteristics

The arillate irises have beards, although the beards of aril and arilbred irises are sparse, looking long and scraggly on the Regelias and like a wide fuzzy patch on the Oncocycluses. And they often are crossed with tall bearded, median and miniature dwarf bearded irises.

The name "aril" refers to all irises and hybrids with arillate seeds, seeds with little fleshy white collars called arils. That characteristic is a botanical one. The term "arilbred" refers to hybrids that result from crosses of aril species plus hybrids of the aril species with true bearded (eupogon) irises.

Characteristics of the some fifty species of Oncocyclus irises, commonly called oncos, include overlapping standards that have a round, domed look. They may be tailored, ruffled or reflexed outward on the sides, a characteristic that is called flagging. The falls are also rounded and they usually tuck under the flower. The falls may be flaring, recurved, rolled under, concave or some combination of these traits. Standards are usually larger than the falls.

Stem heights range from a minute 3 inches to a tall 28 inches and but a single flower grows on each stem. Proportion usually is good, although there are exceptions with large flowers overwhelming short stems or small flowers stuck on tall stems. The stems are almost straight, may have leafy stem spathes and may be either thick and fleshy or thin and wiry.

Veining and stippling or dotting, in strong or muted shades, are an aril characteristic of the flowers' falls and may also occur on the standards. One of the most distinguishing features of onco flowers is the dark, round spot or "signal" that appears at the tip end of the wide beard. The beards are usually broad but may also be linear and range in color from white to nearly black. The flower colors range through a wide variety of colors, patterns and textures, including self, blend, bitone, bicolor and amoena.

Regelia irises of the aril class mostly have stems with two flowers each. Typically, these flowers have standards and falls that are much narrower than the oncos. Standards are sometimes referred to as pagoda-shaped. Both standards and falls are heavily veined. The beards are narrow and brightly colored, occurring on the falls and, to a lesser degree, on the standards. When there is a signal or spot at the end of the beard on each fall, it is usually small and occurs as a V -shaped color spot. The flowers have a more delicate appearance than the oncos and are small to medium in size. Each flower stem is slender and usually tall in proportion to the blossom size.

Hybrids made between Regelia and onco irises usually will have two buds per stem and a flower form that generally demonstrates more Regelia influence and traits than onco traits-that is, they will have heavy veining, a V-shaped signal and color spot. Lilac or lilac-rose ground colors will show dark violet or gray-purple veining with a dark signal spot. Both plants and flowers will be medium in size.

Culture

First of all, select an area with plenty of sun and good drainage, a soil that would suit tall bearded irises or median bearded irises. Gardens with very heavy soils or enough rain to promote rot in tall bearded irises will present a problem for arilbreds as well.

Good sharp drainage will be the key to success. Raised beds may be the answer for those with heavy soil, poor drainage or too much annual rainfall. Arilbreds can tolerate several times the average rainfall of arils' native lands if, and only if, the drainage is excellent. Raised beds and specially prepared soil may be the best answer for some regions.

Prepare the iris bed several weeks ahead of time, mixing in fertilizer and water, then allowing the soil to settle. When ready to plant, make two holes separated by a narrow ridge and press a rhizome into the ridge. Spread the roots to both sides and down. Fill the hole with soil, making sure there are no air pockets around the rhizome and its roots. The top of the rhizome should be about 1 to 2 inches below ground level in heavy soil, 2 to 3 inches below ground level in sandy soil. Place plants about a foot apart.

Keep the root zone moist but not soggy throughout the growing season. Regularly check the soil for moisture to a depth of 3 to 4 inches. Apply a general-purpose fertilizer in the fall and in early spring. Arilbreds are notoriously heavy feeders, so be loyal to your fertilizer program. Have your soil tested to see what is lacking-that is the only sure way to intelligently decide on a fertilizer program. If your soils are acid or neutral, raise the pH level with additions of dolomitic limestone, which will encourage growth and cut down on rot. Once the irises have bloomed, required care will depend on your climate. If summers tend to be dry in your region, stop watering and leave the plants in the ground. Arils and arilbred irises prefer soil with a higher pH than other bearded irises.

The best time for planting arilbred irises is during the period when they are coming out of dormancy. Planting during summer heat is stressful, and so is planting during the late fall prior to severe winter weather. The exact time for optimum planting will depend on the climate. Where they can be left in the ground during the summer, plant them after the worst of the summer heat when they are starting to break summer dormancy. If you have new rhizomes, plant them at the same time, when arils already in the ground are breaking dormancy.

In dividing these irises, note that many of the arils and arilbreds increase rapidly and will have to be divided every year or two to avoid overcrowding. Follow the same schedule of digging and planting soon after the worst of the summer heat when there is still time for root growth before the hard cold of winter.

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