A taxonomic revision of the Hebe parviflora complex (Scrophulariaceae), based on morphology and flavonoid chemistry

Abstract

Two entities have long been recognised at the rank of either species or variety in the New Zealand endemic Hebe parviflora complex but, because one of the critical type specimens had not previously been examined by New Zealand botsnists, there has been uncertainty regarding the correct application Of names. The two entities Can be distinguished on characters of habit, leaves, flowers, leaf flavonoids, and chromosome number, and are accepted here at species rank. H. parvlflora is the correct name for the tetraploid entity previously known as H. parvrflora var. arborea, and H. stenophylla is the diploid entity previously known as H. parviflora var. angustifolia (the autonym var. parviflora has not been used in any recent treatments). H. stenophylla has several distinct geographic races and new names are provided at varietal rank for two of these: var. hesperia occurs in limestone areas near the north‐west coast of the South Island, between Cape Farewell and the Heaphy River; var. oliveri occurs on exposed bluffs on Stephens Island in Cook Strait. Circumscription of these varieties leaves var. stenophylla comprising a range of morphological forms whose relationships require further elucidation. A comparative study of leaf flavonoids identifies flavonoid characters that clearly distinguish H. parviflora and H. stenophylla, and the profiles of these species are compared with those of the related species H. strictissima and H. traversii. Historical factors affecting the distribution of H. parviflora and H. stenophylla are discussed, and descriptions, distribution maps, and illustrations of diagnostic morphological characters are provided for all taxa.