Article from Bean's Trees and Shrubs Hardy in the British Isles
Recommended citation
'Hebe dieffenbachii' from the website Trees and Shrubs Online (treesandshrubsonline.
A shrub of wide-spreading habit 3 to 4 ft high. Leaves narrow-oblong, 2 to 4 in. long, 1⁄2 to 1 in. wide, pointed, thick in texture, rather pale green, the base stalkless and partially clasping the stem. Racemes showy, produced in pairs a little below the apex of the shoot in the leaf-axils, 3 or 4 in. long, 3⁄4 to 1 in. wide, densely crowded with blossom. Flowers 1⁄4 in. diameter, purplish lilac or white. Bot. Mag., t. 7656.
Native of the Chatham Islands, where it was discovered in 1841 by Dieffenbach. It is closely allied, and bears a considerable resemblance to H. speciosa, from which it differs in its generally narrower, paler green sessile leaves, its round, not angled stems, and in the seed-vessel being about thrice (instead of twice) the length of the calyx. It is tender.