blue vervain

not listed

NNR - Unranked

SNR - Unranked

not listed

FACW - Facultative wetland

FACW - Facultative wetland

FACW - Facultative wetland

Blue vervain (var. scabra) is an erect, perennial forb that rises on one or two stems from an underground horizontal stem (rhizome) and fibrous roots. It is usually 16″ to 60″ tall, though in favorable conditions it may reach more than 7′ in height. It often forms colonies.

The stems are annual, erect, stout, moderately to strongly square, and branched near the top. They are green to reddish and moderately to densely covered with spreading to appressed hairs.

The leaves are opposite, lance-shaped to oblong lance-shaped or narrowly egg-shaped, unlobed, 1½″ to 8″ long, and ⅝″ to 1¾″ wide. They are about 5 times as long as wide. They are on short, ⅜″ to 1″ long leaf stalks (petioles). The petioles are usually winged toward the top. The leaf blades are rounded, angled, or short tapered at the base, and tapered to a sharp point at the tip. They do not clasp the stem at the base. They have a prominent midvein, several lateral veins that arch toward the tip, and a network of smaller veins between the lateral veins. The lateral veins end before reaching the margin. The upper and lower surfaces are green and sometimes rough to the touch. They are sparsely to moderately covered with short, inconspicuous, loosely appressed, non-glandular hairs. The margins are coarsely toothed with sharp, forward pointing teeth. There is often a pair of small leaves rising from the leaf axils.

The inflorescence is a branched group (panicle) of 5 to many spikes at the end of the stem and branches. The spikes are erect or strongly ascending, unbranched, ¾″ to 8″ long, and noticeable pointed at the tip. They are short and moderately stout when young, greatly elongated and slender at maturity. The flowers are densely crowded and spirally arranged on the spike. They bloom from the bottom up and only one to a few complete rotations of the spiral are in bloom at any one time. Each blooming flower overlaps adjacent blooming flowers.

Each flower is ⅛″ to ¼″ in diameter. There are 5 sepals, 5 petals, 4 stamens, and 1 style. The sepals are green, and are united at the base into a narrowly bell-shaped tube (calyx), then separated into 5 short teeth that are unequal in length. The calyx is 1 ⁄16″to ⅛″ long. The modified leaves (bracts) at the base of each flower are narrowly lance-shaped, sharply pointed, and 1 ⁄16″to ⅛″ long. They are slightly shorter than the calyx. The petals are purple to purplish-blue, rarely pink or white, and ¼″ to ⅜″ long. They are fused at the base into a slender, funnel-shaped tube then separated into 5 spreading lobes. The lobes are ¼″ to 3 ⁄16″ in diameter and blunt to rounded at the tip. The flowers are not fragrant.

Each flower produces a cluster of 4 reddish-brown nutlets that are enclosed in the persistent calyx but are exposed at the tip. Each nutlet is narrowly oblong to narrowly oblong elliptic in outline and 1 ⁄32″ to 1 ⁄16″ long. They may be faintly ridged on the bottom and have a few faint cross ridges toward the top.

16″ to 60″

Purple to purplish-blue

Blue vervain (Verbena hastata var. hastata) lower, larger leaves have 1 or 2 lobes near the base.

Moist. Marshes, meadows, fields, swamps, roasdside ditches. Full sun.

July to September

Sources

7, 24.

Native