St John's wort, Hypericum perforatum, close up showing clusters of the yellow flowers with protruding stamens against dark green background.

St John's wort, Hypericum perforatum, showing clusters of the yellow flowers with protruding stamens against dark green background.

St John's wort, Hypericum perforatum, showing clusters of the yellow flowers with protruding stamens.

Poppy, Iceland poppy, Papaver nudicaule 'Garden gnome' buds. 2 hairy buds closely entwined.

Rose root, Rhodiola rosea, used in herbal medicine. Close up of single flower head, selective focus.

Rose root, Rhodiola rosea, used in herbal medicine. Close up of single flower head, selective focus.

Rose root, Rhodiola rosea, used in herbal medicine. Close up of flower heads, selective focus.

Rose root, Rhodiola rosea, used in herbal medicine. Close up of single flower head, selective focus.

Rose root, Rhodiola rosea, used in herbal medicine. Close up of flower heads, selective focus.

Rose root, Rhodiola rosea, used in herbal medicine. Close up of single flower head, selective focus.

Rose root, Rhodiola rosea, used in herbal medicine. Close up of single flower head, selective focus.

Rose root, Rhodiola rosea, used in herbal medicine. Close up of flower heads, selective focus.