Verbena urticifolia L. - White Vervain

Verbena urticifolia plant

Family - Verbenaceae

Stems - To 2m tall, 4-angled, from a woody caudex, hollow, simple or branching, scabrous, pubescent, herbaceous, erect, single or multiple from base.

Verbena urticifolia stem

Leaves - Opposite, decussate, petiolate. Petioles to 3cm long, winged by decurrent leaf tissue. Blades to 15cm long, 8cm broad, serrate, scabrous, pubescent, deep green above, light green below, lanceolate to ovate-lanceolate, abruptly contracted at base. Veins depressed on adaxial surface, expressed on abaxial surface.

Verbena urticifolia leavesPressed leaves.

Inflorescence - Terminal and axillary racemes to +/-25cm long, 6mm in diameter. The flowers loosely arranged, not crowded or overlapping. Racemes compact in flower, quickly elongating in fruit. Axis sparse pubescent. Each flower subtended by one small acute bract. Bracts to +/-1mm long, green.

Flowers - Corolla white, 5-lobed (weakly bilabiate with one notched upper lobe and 3 bottom lobes), 2.5mm broad. Corolla tube to 3mm long, pubescent externally, bearded internally. Stamens 4, didynamous, included. Filaments very short. Anthers greenish. Ovary superior, green, glabrous, .5mm long, cylindric. Style green, glabrous, -1mm long, with a lateral appendage. Appendage -2mm long. Stigma capitate. Calyx green, antrorse pubescent externally, glabrous internally, 5-lobed, 2.2mm long. Lobes triangular, +/-.2mm long, acute. Uppermost lobe is shorter than the others.

Verbena urticifolia calyxCalyx close-up.

Verbena urticifolia flowerFlower close-up.

Flowering - June - October.

Habitat - Pastures, prairies, waste ground, roadsides, railroads.

Origin - Native to U.S.

Other info. - This is a very common plant in early summer. It can be found throughout Missouri.
V. urticifolia is easy to identify in the field because of its tiny white flowers and long, skinny inflorescence branches.

Photographs taken in the Ozark Scenic Riverways, Shannon County, MO., 6-22-04.


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