All iris have a particular flower shape. While a daisy has all the petals the same shape radiating from the center like a pinwheel, an iris flower has a distinct top and bottom. The flower petals that stand up like flags are called the standards (an old word for flag, by the way). The bottom petals which orient downwards are called the falls; they act as well-marked landing platforms for the insect pollinator.
A very common iris found along ponds and streamsides here in Delaware County is the Yellow Flag (Iris pseudacorus). Like many plants in our landscape, it is not native to here but was introduced from Europe and it is now naturalized. This water-loving plant develops into a massive clump and spreads itself liberally through seed which are dispersed every time there is flooding. It is sometimes planted in gardens but it often quickly overwhelms.
There are two types of iris which we are most likely to find in Delaware County gardens. Siberian Iris (Iris siberica) is another Eurasian native whose flower structure (pictured left) is similar to the Yellow Flag. However it is much better behaved in the garden. It forms sturdy clumps and its flowers are mostly different shades of blue, although there are white and pink varieties as well.
German Bearded Iris (Iris germanica)are the best known of the iris we are likely to find in Delaware County gardens. They may be a bit more fussy in order to grow and flower well, but the sumptuous flowers (pictured right) and their broad color range make them worth the extra work. The basic flower structure of standards and falls is still evident.
Besides the difference in flowers Siberian and German Bearded Iris are easy to distinguish when not flowering. The last picture below shows the base of a Siberian iris plant on the right – note the clump of skinny grass-like leaves. On the left is a typical Bearded Iris growth habit – note the somewhat flattened fan-shaped clumps.