Most are fooled by the Black Hollyhock's deep purple-blue petals, which to the untrained eye appear a deep shade of black. The petals often boast a vivid hint of red, which only adds to their beauty. It's an ideal specie to plant close to a wall or at the back of a border, and one that will add instant glamour to an otherwise subtle garden. These black flowers are able to thrive in an array of climates.
Source: seagreenandsapphire.wordpress.com
In addition to the Black Hollyhock, the Hollyhock 'Nigra' is another exceptionally beautiful black flower. This unique specie boasts pretty chocolate-hued flowers with almost black centres that thrive in both cool and warm climates – making them a perfect addition to the garden and the home. While many of the 'black' flowers are actually not black at all, they can still provide stunning enhancements to a bouquet, floral arrangement or even vase display.Sources: MNN and Birds and Blooms