Flower:

Dense, 1-sided raceme of 10 to 50 pea-shaped flowers on stalks arising from leaf axils in the upper stem. Flowers are about ½ inch long, the upper petal (the standard) flaring upward, lateral wings below it oval, extending outward. The erect part of the standard (the banner) is about as long as the part that forms the floral tube (the claw) and is typically purplish-pink to blue-violet; the lateral wings can be the same color but are often paler.

The calyx holding the flower is hairless to variously covered in short, appressed hairs and has 5 triangular lobes, the upper lobes shorter and broader than the lower, and all shorter than the calyx tube. Flower stalks are very short and variously covered in short, appressed hairs. The base of the calyx lacks a bulge or is only slightly swollen where it attaches to the stalk.

Leaves and stems:

Leaves are compound with 5 to 12 pairs of leaflets, and a branched tendril at the end that entwines surrounding vegetation for support. Leaves can be up to 10 inches long and 2 inches wide but 6 inches or less is typical. Leaflets are about ¾ inch long and 1/8 inch wide, linear to oblong-elliptic, toothless, rounded to pointed at the tip, often with a tiny, abrupt point at the tip (mucronate). Both surfaces are covered in short, appressed hairs.

At the base of the leaf stalk is a pair of narrow, sharply pointed, leafy appendages (stipules) that are ¼ to 1/3 inch long and short hairy, particularly around the edges. Stems are vining, multi-branched and sprawling, 4-sided with distinct ridges and variously covered in very short hairs.

Fruit:

Fruit is a flattened pea pod up to 1 inch long, containing 2 to 8 round to oval seeds.

Notes:

Tufted Vetch is most easily confused with Hairy Vetch (Vicia villosa), which usually has distinctly longer, spreading hairs on stems, stalks and calyces where Tufted Vetch is usually more sparsely covered in short, appressed hairs, but hairs alone may not lead to a positive ID. A post on iNaturalist details differences in the flowers that can further distinguish them (see also the image below). In a nutshell:

• On V. cracca, the banner is about as long as the claw, where on V. villosa the banner is about half as long as the claw so flowers look more elongated. This is pretty obvious and may even be detected from some distance.
• On V. cracca, the calyx base is not swollen or is only slightly so, where on V. villosa the base is distinctly swollen so it bulges beyond where the flower stalk is attached.
• On V. cracca, the calyx lobes are all triangular and relatively short, where on V. villosa the lobes are narrow and elongated, more dramatically so on the lower lobes.

Vicia cracca is also perennial where V. villosa is annual, biennial or short-lived perennial. V. cracca is more common in northern Minnesota and V. villosa is more common in the central and southern counties, but reports at EDDMapS and iNaturalist have their ranges starting to overlap, with several reports of V. cracca in and near the Twin Cities Metro area; it is possible some of those reports are mis-IDs due to the ease of mistaking one for the other. In any case, both are weedy and can create dense, tangled mats.

USDA lists 4 subspecies, but they are not well-documented so we do not know what distinguishes one from another. Subsp. cracca, the most common, is present in Minnesota; subsp. tenuifolia (a.k.a. V. tenuifolia) has been recorded a few times in Wisconsin.