The plant commonly known as tare is scientifically identified as Vicia sativa, or Common Vetch, a member of the pea family (Fabaceae). This annual herbaceous plant is widely cultivated globally as a nitrogen-fixing cover crop, valuable for improving soil health. However, its tendency to self-seed means it is also frequently encountered as a field weed in cereal and grain crops. Understanding its physical characteristics is essential for accurate identification.
Overall Structure and Growth Pattern
Common Vetch is an annual plant characterized by a viny, sprawling, or climbing growth habit. Without support, the slender stems trail along the ground, often creating dense mats. When planted near a companion crop, the plant uses specialized structures to climb upward. The thin, branched stems possess a distinctly angular or four-sided cross-section, which aids identification. The maximum height typically ranges from one to three feet.
The plant develops a deep, branched taproot system that can penetrate the soil up to three to five feet, contributing to its drought tolerance. The stems are generally light green and may be sparsely covered with fine, soft hairs (pubescent) or be entirely smooth. In dense plantings, the sprawling plant relies heavily on intertwining stems and surrounding vegetation to achieve an upright posture.
Identifying Features of Leaves and Stems
The leaves of the Common Vetch are recognizable features, arising alternately along the stem. Each leaf is pinnately compound, divided into multiple smaller leaflets arranged on either side of a central stalk. A single leaf typically consists of three to eight pairs of oblong, lance-shaped, or wedge-shaped leaflets.
Individual leaflets are usually between a half-inch to one and a quarter inches long, often ending in a small, spine-like point or possessing a notched tip. A defining trait is the branched, coiling tendril located at the end of the leaf stalk. This tendril wraps tightly around nearby objects, providing support for the plant to climb. At the base of the main leaf stalk, a pair of small, leafy appendages called stipules are visible, often featuring a tiny, dark glandular spot.
Distinctive Flowers and Seed Pods
The reproductive structures offer definitive visual confirmation of the plant’s identity. Common Vetch produces showy, pea-like flowers (papilionaceous), characteristic of the legume family. These flowers are typically a vibrant purplish-pink to reddish-purple color, though white or pale variations are sometimes observed.
The blooms are relatively large for a vetch species, measuring between a half-inch and over one inch in length. They are borne singly or, more commonly, in pairs directly from the leaf axils on very short stalks. The flower structure features a broad, often notched upper petal called the standard, which partially encloses the two wing petals and the lower, fused keel petals.
Following pollination, the flowers give way to elongated, flattened seed pods. These pods measure from one-and-a-half to three inches long. They are initially green and slightly hairy, darkening to brown or black upon maturity. Each pod contains between four and twelve smooth, spherical, dark seeds.
Differentiation from Related Look-Alikes
Accurate field identification requires distinguishing Common Vetch from its close relatives, primarily other species within the genus Vicia. A key difference lies in the flower arrangement: Common Vetch’s flowers are solitary or paired in the leaf axils. This contrasts with species like Tufted Vetch (Vicia cracca), which bears its flowers in dense, elongated clusters called racemes. Narrow-leaved Vetch (Vicia sativa subsp. nigra) is also often confused with the common variety.
The distinction often comes down to the width of the leaflets and the size of the flowers. Common Vetch possesses broader leaflets and larger flowers, typically over three-quarters of an inch long. Hairy Vetch (Vicia villosa) is easily separated by its densely hairy stems and leaflets, contrasting with the sparsely hairy or smooth stems of Common Vetch. Subtle differences in the calyx, the cup-like structure supporting the petals, also provide confirmation.