Hebe parviflora var arborea
Hebe parviflora var arborea (syn Hebe parviflora) is an evergreen large shrub or tree, growing to up to 20 ft (6 m). The green leaves are narrow, spear-shaped, 1–1.4 in (2.5–3.5 cm) long and 0.2 in (4 mm) wide. White flowers in dense spikes, summer. This hebe seems to be fairly hardy in the UK.
This hebe species is found in scrub on hillsides, along streams and forest edges, from near coastal to montane, North Island (and north-east South Island), New Zealand. It is rare in cultivation, both in New Zealand and the UK.