Geographic variation in morphology and flavonoid chemistry in Hebe pubescens and H. bollonsii (Scrophulariaceae), including a new infraspecific classification for H. pubescens

Abstract

Geographic variation in morphology, leaf anatomy, and flavonoid chemistry is appraised in Hebe pubescens, H. bollonsii, and allied plants from islands of outer Hauraki Gulf, North Island, New Zealand. The circumscription of H. pubescens is modified to include plants from Great Barrier, Little Barrier, and the Mokohinau Islands, as well as the Coromandel Peninsula and immediately surrounding islands. A new infraspecific classification is proposed for H. pubescens, wherein three subspecies are recognised. Subspecies pubescens occurs on the Coromandel Peninsula and immediately surrounding islands, and also at Papanui Point on the western coast of the Firth of Thames. Subspecies rehuarum occurs on Great Barrier Island. Subspecies sejuncta occurs primarily on the Mokohinau Islands and Little Barrier Island, with a single plant also known on Great Barrier Island. Populations of H. pubescens probably form a cline of variation, and some forms of subsp. sejuncta share morphological features with H. bollonsii, which is here considered restricted to the Poor Knights Islands, the Hen and Chickens Islands, and nearby areas of the Northland coast. Possible relationships of H. pubescens and H. bollonsii are discussed. A key to the taxa of Hebe pubescens is provided.