Vincetoxicum darvasicum 1 Copenhagen Bot Garden 130625 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum darvasicum 2 Copenhagen Bot Garden 130625 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum fuscatum 2 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum fuscatum 3 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum hirundinaria ssp adriaticum 1 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum hirundinaria ssp hirundinaria 3 Löderups Strandbad, Skåne 080531 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum hirundinaria ssp hirundinaria 4 Bergshamra, Solna, Uppland 030922 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum hirundinaria ssp hirundinaria 5 Bergshamra, Solna, Uppland 030922 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum medium 2 Bergianska 060620 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum nigrum 2 Copenhagen Bot Garden 130625 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum nigrum 3 Copenhagen Bot Garden 130625 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum rossicum 1 Storrs, Connecticut 900616 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum rossicum 2 Brunnby 080815 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum rossicum 3 Brunnby 080815 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum stepposum 3 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum stepposum 4 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum fuscatum 1 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum hirundinaria ssp adriaticum 2 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum hirundinaria ssp hirundinaria 1 Copenhagen Bot Garden 130625 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum hirundinaria ssp hirundinaria 2 Sundsgården, Raus, Skåne 780624 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum medium 1 Bergianska 060620 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum nigrum 1 Copenhagen Bot Garden 130625 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum stepposum 1 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Vincetoxicum stepposum 2 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).