Cosmos, Flower growing outdoor silhouetted at sunset.

Cosmos, Flower growing outdoor silhouetted at sunset.

Pasque flower, Pulsatilla pratensis, Fluffy seedhead with dark strands silhouetted against pink and blue mottled background.

Oak, Common oak, Quercus robur, Side view of fairly mature tree with no leaves, silhouetted against the misty dawn sky in an English field.

Hogweed, Heracleum sphondylium. Drying, skeletal stems of Hogweed silhouetted against pale blue sky.

Oak, Quercus robur, silhouetted tree against warm orange coloured sky, Welwyn Garden City, Hertfordshire, England.

Oak, Quercus robur, silhouetted tree against warm orange coloured sky, Welwyn Garden City, Hertfordshire, England.

Oak, Quercus robur, silhouetted tree against warm coloured sky, Welwyn Garden City, Hertfordshire, England.

Beech trees in winter silhouetted against pale blue sky.

Greece, Flowering stems of Agave cultivar silhouetted against pale sky.

USA, Arizona, Saguaro National Park, Saguaro cactus silhouetted against blue sky in soft light, framed by branches of another in foreground.

Ireland, County Monaghan, Rossmore Forest Park, Winter sun rays shining through part silhouetted conifer trees.