Pin and Thrum on Primroses
Primula vulgaris (Primroses) are a common rosette forming herbaceous perennial, with solitary flowers which rise in clusters during springtime. They’re often an annual addition to borders, meadows, and wildlife gardens. Interestingly, and unbeknown to most gardeners is the heterostylous dimorphism first described by Charles Darwin, known as ‘pin or thrum’ formation. Pin or thrum involves the stamen and stigma being differently positioned in individual plants to avoid self-pol