While shingle beaches may disappoint those seeking sandcastles, the pebbly shore at Hayling Island in Hampshire offers a haven for wildlife. Above the high-tide mark, beach recycling has been used to maintain the shingle, which absorbs wave energy and provides natural protection against coastal erosion. The well-drained, nutrient-poor substrate also proves ideal for plants adapted to harsh conditions.
Among the late-flowering yellow horned poppies, pink thrift and vibrant viper's bugloss, one plant in particular has stolen the spotlight. Broad clumps of sea kale (Crambe maritima) have attracted the attention of a trio of small white butterflies (Pieris rapae). A female is nectaring on the honey-scented flowers while two males compete for her attention, fluttering and spiralling upwards in an attempt to outmanoeuvre each other.
The sexes are easy to tell apart: males have a single black spot on each forewing, while females have two merging marks below the centre of each forewing, in addition to the single spot. The sooty appearance of the wing tips and leading edges suggests these individuals have recently emerged, and the summer brood generally has darker markings than the spring brood. When a shadow falls across the female, she claps her wings shut, revealing clotted-cream undersides.
Once mating occurs, the female will lay her conical eggs singly on the undersides of the lobed, wavy-edged sea kale leaves. This long-lived perennial is a primary larval food plant for the velvety green caterpillars, whose powerful jaws can tackle the thick, waxy cuticle.
Sea kale is considered a culinary delicacy, with its blanched stems, florets and seed pods prized by foragers. However, as the author notes, with a border terrier scampering by and cocking its leg against the plant, it is perhaps best left for the butterflies.
