May is the month for the spring ephemerals to bloom. What are spring ephemerals? They’re the woodland wildflowers that blossom prior to the deciduous trees leafing out. They require full sunlight before the woods are in deep shade from the fully developed leaf canopy.
Large-flowered trilliums are some of the most well-known spring ephemerals. When their petals turn pink, their blooming time is ending. There are also many smaller wildflowers blossoming in May in the deep woods that often go unnoticed. Some are the violets.
Viola is the generic name for these plants and for the cultivated pansies. The violet family has about 650 species in 16 genera. The genus arose in South America, but greater diversity now is in the Northern Hemisphere. Gray’s Manual of Botany lists about 50 species for the United States, and Fassett’s Spring Flora of Wisconsin lists 21 species for our state. It’s no wonder that the blue violet is the state wildflower. What’s confusing is that there are nine blue or purple violets statewide, but technically, only one – Viola sororia – is the state flower.
Most people are satisfied merely to recognize a violet and describe it by its color – usually blue, purple, yellow or white. Some of the common names do indicate specific, easily recognized differences. Several that stand out are the American dog, marsh blue, birdfoot, kidney-leaved, Canada, long-spurred and downy yellow.
The kidney-leaved violet, V. renifolia, does have distinctly kidney-shaped leaves that are wider than they are long, and all of its petals are beardless. Look for this violet in rich woods rather than in the swampy conditions favoring the marsh blue violet. Habitats often provide important clues when identifying violet species.
Locate a large concentration of violets on your property, take up an entire plant and carefully study its details. (A good magnifying lens is very helpful when studying violets.) Violets are grouped with irregular flowers in Newcomb’s Wildflower Guide, one of my favorite field guides.
Each blossom has five petals: the two upper petals are smaller; the two lateral petals are larger; and the one basal (lower) petal is also large and serves as a landing platform for bees, insects and butterflies that are intent upon obtaining nectar.
Violets are either stemless or stemmed, a concept that may be confusing if you do not learn the terminology. If the blossom arises directly from the ground as a leafless stem, such as a dandelion, it is said to be stemless.
Blossoms connected to leafy stems – such as the beautiful, large Canada violet or the abundant blue American dog violet – are called stemmed violets. In other words, the thin portion of the plant, beginning at the ground, that supports the leaves and extends up to the node of the uppermost leaf, is the stem. The slender structure, often quite short, extending beyond that and supporting only the blossom is the stalk or scape.
Learn to refer to the leaf stems as petioles. At the base of violet petioles are tiny appendages called stipules, whose shapes can be diagnostic in identifying violet species. Some, for example, are toothed, such as on the downy yellow violet. Others are smooth, as on the smooth yellow violet.
Critical in identifying these beautiful, little wildflowers is the bearding on their petals. Some have only their two lateral petals bearded while all petals on others are smooth. Certain petals are strongly veined on some plants, and some violets are perfumed while others are not.
The downy yellow violet, V. pubescens, gets its name from the fuzzy or hairy stems and undersides of the very broad and prominently veined leaves. It prefers upland, dry woods.
The most common blue violet in our area, growing abundantly in lawns, is the American dog violet, V. conspersa. Look at the lower sides of the leaves to see their dotted surface. The latest and tallest violet blooming in our woods is the Canada violet. Its white petals have a purple back surface, and the petals have yellow at the base and deep purple veins on three of them.
Get to know these dainty, native wildflowers to appreciate their beauty in the early spring.