Irises are one of the most beloved perennial flowering plants, popular for their rainbow array of colors. They are an easy plant to grow and require little care and maintenance. Irises are sought after for xeriscape gardening because they need little water. Iris species grow in heights varying from several inches to several feet. They bloom in the early to late spring and many are re-bloomers.
Iris plant classification grew out of the work of Swedish botanist and medical doctor Carolus Linneaus, who wrote 180 books describing plant species in detail. The Linneaus system of scientific classification of all living things became the standard by the early 19th century. Plants are classified as the Plantae kingdom.
The U.S. Natural Resources Conservation Service classifies iris in the subkingdom of Tracheobionta, which are vascular plants. Its superdivision is Spermatophyta, or seed plants, and its division is Magnoliophyta, or flowering plants. The class, subclass, order and family are Liliopsida, Liliidae, Liliales and Iridaceae.
Genus and Species
There are 260 species in the classification of the Iris genus. Iris is the scientific name as well as the common name. Its name is derived from Greek mythology of the goddess Iris who walked a rainbow path. Iris is commonly known in North America as "flag." They have three upright petals known as "standards" and three that hang down called "falls." The genus is separated into two main groups: rhizomatous and bulbous.
Rhizomes are underground stems that serve as storage for food produced by the leaves. Offshoots develop yearly from the rhizomes and are used as transplants. Bearded, crested and beardless are the three divisions within the rhizomatous classification. The bearded iris has a line of dense fuzz down the middle of each fall. Crested irises have a taller cockscomblike beard and beardless have none.
Bulbous irises are beardless and fall into two categories: scorpiris and xiphium. These categories describe differences in their root systems. Xiphium bulbs are rootless during the dormant phase. Roots on the scorpiris iris persist when they are dormant. Some xiphium iris bulbs have a netlike covering. Dutch, Spanish and English iris are of the xiphium classification.