Family: Proteaceae

Several species of this small genus of 11 species of nut-bearing, evergreen trees come from the warm, eastern coastal areas of Australia. The dense, dark green, leathery leaves are arranged in whorls and the long, pendulous spikes of small flowers are followed by the round fruit containing the hard-shelled nuts. These trees are grown commercially in Australia, not only for their delicious nuts, but also for the high quality oil yielded by the kernel and the substances contained in the hull which are used for tanning leather. The trees are variable producers and unseasonal dry spells during spring and early summer will reduce the crop and affect the size and quality of the fruit. These trees are difficult to propagate by vegetative methods, and are now generally being increased by new grafting methods.

Species

M. integrifolia is a large, round-headed tree which grows to around 18 m (60 ft) tall. When young, the leaves are coarsely toothed, generally becoming entire at maturity and growing 10-30 cm (4-12 in) long. The smooth-shelled nut is 1-3 cm (½-1 in) in diameter.

M. ternifolia grows to 5 m (16 ft) tall, with small, bitter, inedible nuts.

M. tetraphylla is a large, handsome, round-headed tree, distinguishable by its finely serrated leaves, 10-50 cm (4-20 in) long. It reaches heights of around 18 m (60 ft). The rough-shelled nuts are 1-4 cm (½-1½ in) in diameter. Selected, heavy-bearing varieties with good-quality nuts are available from specialist growers.

Cultivation

These trees are sensitive to frost, so in climates prone to frost they should be grown as young foliage plants in an intermediate greenhouse or conservatory. It is unlikely they will bear nuts under glass. Grow in pots of soil-based potting compost and provide bright light, but shade from direct sun. They are deep-rooted trees and so would be best in deep containers or even planted in a soil border. Outdoors grow in deep soil with a high organic content and in full sun.

Climate

Warmer parts of zone 10 and above.