A much-branched evergreen shrub 2 to 5 ft high in cultivation but up to 20 ft in the wild; young shoots often minutely downy. Leaves closely arranged in the usual four superposed rows, narrowly oblong, tapered about equally to both ends, finely pointed, margins slit or entire, 1⁄2 to 1 in. long, 1⁄10 to 1⁄6 in. wide, dark bright green above, paler beneath, midrib prominent beneath, but with no visible veins; stalk very short. Flowers produced near the ends of the shoots in June in usually one or three rounded, corymbose clusters 3⁄4 to 1 in. wide. Corolla pale lavender-blue to white, 1⁄4 to 1⁄3 in. wide, with a short funnel-shaped tube and four lobes, the rearmost (or inner) lobe the largest; corolla-tube as long as calyx. Calyx usually three-lobed, the anterior lobe broader than the others or more or less deeply notched. Flower-stalks minutely downy.
Native of the North Island, New Zealand, discovered by Richard Cunningham in 1834 in the Bay of Islands. Its distinguishing characters are the downy shoots and flower-stalks, the corymbose inflorescence, the usually three-lobed (rarely four-lobed) calyx. It is a neat and pleasing shrub and has been successfully cultivated in the Edinburgh Botanic Garden for over half a century. At Kew it is killed or injured in severe winters. The so-called variety “trisepala” has no proper standing, being based merely on the absence of a bilobing of one calyx segment, thereby making the calyx three-lobed, which is its normal condition in this species.
H. menziesii (Benth.) Ckn. & Allan – This species was described by Bentham from specimens collected by Menzies at Dusky Bay, Fiordland, South Island, in 1791, but no plants agreeing with these specimens have been found there since. Dr Moore considers that the plants usually placed under H. menziesii should be referred to H. divaricata (Cheesem.) Ckn. & Allan, which differs from H. diosmifolia in the following characters: leaves entire; anterior calyx-lobes free for most of their length; corolla-tube longer than calyx.