Cow parsley 'Ravenswing'. Anthriscus are annuals, biennials or perennials, having beautiful fern-like delicate foliage and umbels of tiny white flowers suffused Pink. Ravenswing is a decorative cow parsley, the wonderful deep-purple leaves and pink-tinged flowers make this a lovely late spring flowering perennial. It is a short-lived , but rejuvinates from seed. The chocolate purple leaves resonate in the landscape from spring too autumn. Prefers a shaded or semi shaded position and some consistent watering.