Peony colors range from white to light pink or blush, then the darker pinks and reds (as shown in the photos above). More modern breeding programs have produced other colors such as coral and yellow, but the Peony Garden includes only the more traditional colors. I seem to remember seeing a few of the coral shade blooms in previous years, but not this year. I'm guessing they were removed to keep the garden colors more in line with the historical shades.
Some of the flowers have a very strong fragrance, while others have a very delicate scent, or none at all.
Peony flower types include single-style flowers (such as the pink peonies, below) and the more familiar double-style flowers (such as the white ones below), and a gradation of styles in between.
The majority of peonies at Nichols Arboretum are double peonies, although my favorites are often the single-type flowers, probably because they are less common.