Verbena 1a Desert Botanical Garden, Phoenix, Arizona 130426 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena 1b Desert Botanical Garden, Phoenix, Arizona 130426 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena 1c Desert Botanical Garden, Phoenix, Arizona 130426 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena bonariensis 2 Lund Bot Garden 130627 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena bonariensis 3 Lund Bot Garden 130627 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena bonariensis 4 Lund Bot Garden 130627 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena bonariensis 5 Lund Bot Garden 120822 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena bonariensis 6 Lund Bot Garden 120822 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena canadensis 2 Lund Bot Garden 120908 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena canadensis 3 Lund Bot Garden 120908 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena canadensis 4 Lund Bot Garden 120908 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena canadensis 5 Lund Bot Garden 120908 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena hastata 2 Lund Bot Garden 070718 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena lasiostachys 1 Copenhagen Bot Garden 130611 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena officinalis 1 Svaneke, Bornholm DK 090624 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena officinalis 2 Svaneke, Bornholm DK 090624 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena bonariensis 1 Lund Bot Garden 130627 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena bonariensis 7 Lund Bot Garden 100701 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena bonariensis 8 Lund Bot Garden 130627 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena canadensis 1 Lund Bot Garden 070720 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena hastata 1 Lund Bot Garden 070718 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena lasiostachys 2 Copenhagen Bot Garden 130611 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena lasiostachys 3 Copenhagen Bot Garden 130611 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena lasiostachys 4 Copenhagen Bot Garden 130611 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena officinalis 3 Svaneke, Bornholm DK 090624 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena officinalis 4 Svaneke, Bornholm DK 090624 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena officinalis 5 Svaneke, Bornholm DK 090624 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Verbena officinalis 6 Svaneke, Bornholm DK 090624 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).