Iris is a genus of some 260 species of flowering plants with showy flowers. It takes its name from the Greek word for a rainbow, referring to the wide variety of flower colors found among the many species. As well as being the scientific name, iris is also very widely used as a common name; for one thing, it refers to all Iris species, though some plants called this belong to other closely related genera.
In North America, a common name for irises is 'flags'. It is a popular garden flower in the United States.
Some irises grow in deserts, some in swamps, some in the cold far north, and many in temperate climates. Bearded Iris and Siberian Iris are two of the most common types of iris grown.
Irises are very hardy and do not need a lot of maintenance. Some of the Irises in my wife's garden were given to her by my great grandmother and they have be in the family now for over 100 years.
My favorite technique for photographing them is fairly simple. I use my 70-200mm zoom lens and then add my 1.4 extender. This gets me to 280mm of focal length. I generally shoot a f4 to f5.6 to keep my DOF shallow. I look for flowers that have a good seperation from the others and I have more flowers in the background. This allows for nice sharp focus on the target flower, but gives me that beautiful soft palet of colors for backgrounds.