Dulwich Picture Gallery, London Ghostly ferns, writhing peppers, exploding flowers… this magnificent show digs deep into photography’s almost symbiotic relationship with the natural world A celery plant leans nonchalantly against a wall, long limbs rising to a tousled leafy head. A red onion gleams like an ancient bronze orb. Peas are black pearls in their casket pods and four Ailsa Craig onions, arranged in a basket, resemble Russian minarets: a quartet of spires pointing up to the heavens.