Flower:

Irregular 5-petaled yellow flower about ½ inch (to 13 mm) long at the end of a stalk arising from a leaf axil. The 2 lateral petals have small tufts of yellow hairs at the base (bearded). The lower petal has dark purple-black veins radiating from the center and forms a short spur at the back. All petals may be purple-tinged on the back. Sepals are narrowly egg-shaped to lance-linear, blunt or pointed at the tip. Flower stalks are variously hairy to hairless.

Leaves and stem:

There are both stem and basal leaves, though basal leaves may be absent; color is green to gray-green. Mature leaves are up to 3 inches (to 75 mm) long, as long as or longer than wide, heart-shaped, blunt to pointed at the tip. Edges have blunt teeth and are fringed with short hairs; surfaces are hairy, more densely on the lower surface. At the base of a leaf stalk is a pair of leafy appendages (stipules) that are egg-shaped and sometimes notched at the tip. Stems are hairy, single or multiple from the base.

Fruit:

Both petalled (chasmogamous) and petal-less, self-pollinating (cleistogamous) flowers produce fruit, in an ovoid capsule up to about ½ inch (7 to 14 mm) long, hairless to densely hairy, initially green and dangling, becoming erect when mature and drying light to medium brown. The mature capsule splits into 3 sections, each containing many orange-brown seeds 2.3 to 3 mm long.

Notes:

Downy Yellow Violet is one of two yellow-flowered violets native to Minnesota, the other is Yellow Prairie Violet (Viola nuttallii), which, as its common name suggests, is a prairie species where V. pubescens is a woodland species. Other distinctions are the leaf shape, which is quite different between the two, and location within the state, with V. nuttallii rare, found only in a handful of locations near the South Dakota border, and V. pubescens common, found all across the state.

Now for the surprise: forget everything you thought you knew about V. pubescens. Dr. Harvey Ballard, the authority on North American violets, had made a case that what was considered a variable V. pubescens species should be split into two, the offshoot being Viola eriocarpa, Smooth Yellow Violet. While it may be similar in appearance to V. pubescens, it is hairless to sparsely hairy, leaves are pointed at the tip (often abruptly narrowed near the tip), stem leaves are evenly distributed, it usually has multiple stems from the base and two or more basal leaves, stipules are narrowly egg-shaped, and stems tend to be prostrate at the base during flowering and become erect in fruit. By comparison, V. pubescens is more densely hairy, leaves are more blunt to rounded at the tip, stem leaves are clustered in the upper quarter of the stem, stems are usually single from the base, it usually lacks basal leaves (rarely 1 or 2), stipules are broadly egg-shaped, and stems are all erect throughout the growing season. Ballard also notes that V. eriocarpa seems to be the more common of the two.

I dare say our images seem to be a closer match to V. eriocarpa, but sorting this out will be a priority in the coming field seasons. Note that it could be years before the existing herbarium records are all reviewed and revised distribution maps finalized. Stay tuned.