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The new site offers several benefits over the existing website, including real coordinate mapping, giving a clearer view of the density of documentation as well as more precision about plant distributions and their link to landforms. We will also have the ability to update species pages more regularly, both in terms of new collections and as more existing Michigan specimens are georeferenced. In addition, we have a better photo display, and offer indented keys.

Verbena

All of our species are known to hybridize with one or more other species, but in Michigan only V. hastata × V. urticifolia is at all frequent. The corollas are normally some shade of blue to purple or white, with rose-colored forms occurring rarely.

1. Spikes (even excluding corollas) at least (8–) 12 mm thick; plant ± spreading-decumbent, with incised-pinnatifid leaves.

V. bracteata

1. Spikes (at least excluding corolla) less than 8 mm thick; plant stiffly erect, with leaves unlobed or lobed only at the base (pinnate only in V. officinalis).

2. Leaves linear-lanceolate, 5.5–12 times as long as broad, the blade less than 1.5 cm wide and tapering into ± indistinct petiole; plant glabrous or with scattered, mostly appressed stiff hairs.

V. simplex

2. Leaves ovate-lanceolate or broader, 1.3–6 (–6.3) times as long as broad, (1.3–) 2–6.5 cm wide, sessile to subsessile or mostly with distinct petiole; plant with hairs on stems and leaves numerous and/or ± spreading.

3. Leaves (except uppermost) deeply pinnately lobed or incised; flowers at maturity remote in spike; stem glabrous or sparsely scabrous.

V. officinalis

3. Leaves at most (V. hastata) with 1–2 lobes at base of the blade; flowers remote or crowded; stems glabrous or pubescent.

4. Plant ± densely hoary-pubescent; leaves sessile (or the lower subsessile on winged petioles), 1.3–3 times as long as broad; limb of corolla ca. 7–11 mm broad; calyx over 3.5 mm long.

V. stricta

4. Plant with more sparse pubescence, not hoary; leaves distinctly petioled, 2–6.3 times as long (including petiole) as broad; limb of corolla ca. 2.5–4 mm broad; calyx less than 3.5 mm long.

5. Spikes with flowers and fruit (except sometimes lowest ones) densely overlapping; corolla blue to purple (rarely rose), the limb ca. 2.8–4 mm broad; style 1–1.5 mm long, noticeably exceeding calyx after shedding of corolla; calyx 2.3–3 mm long; leaves often with 1–2 lobes at base of blade.

V. hastata

5. Spikes with flowers (except in bud) and fruit distinctly separated on the axis; corolla white, the limb ca. 2.5 mm or less broad; style ca. 0.4–0.6 mm long (or less), scarcely if at all exceeding calyx; calyx (1.5–) 1.8–2.3 (–2.5) mm long; leaves all unlobed.

V. urticifolia

All species found in Verbena

Verbena bracteataPROSTRATE VERVAIN, CREEPING VERVAIN 
Verbena hastataBLUE VERVAIN 
Verbena officinalisEUROPEAN VERVAIN 
Verbena simplexNARROW-LEAVED VERVAIN 
Verbena strictaHOARY VERVAIN 
Verbena urticifoliaWHITE VERVAIN 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. January 29, 2023. https://www.michiganflora.net/genus.aspx?id=Verbena.