Family: Xanthorrhoeaceae
Common Name: Black Boy, Grass Tree

This unusual and fascinating genus of around 15 species is native only to Australia. Actually very primitive plants, they are unlike any other known plant. They are slow-growing, long-lived, grass-like plants, which sometimes survive for several centuries and are thought to be among the oldest living plant species.

They have a stem both above and below the ground, the stem above the ground being palm-like and topped with a thick clump of long, arching, tough, wiry leaves. Young plants are simply tufts of leaves, some taking around twenty years to form a trunk. The flower spikes are composed of densely packed, small, white to yellow flowers, followed by seed capsules which are carried along the length of the spike. Flowering times in the plants' natural habitats are extremely varied and often dependent on previous bushfires.

Grass trees are becoming better known and a few species are available. Where frosts occur, they have to be grown in a cool to intermediate greenhouse or conservatory.

Species

X. arborea is a woody plant, with a 2 m (6 ft) high trunk, grayish green leaves and a long, thick flower spike.

X. australis has a dark trunk and narrow, green leaves, the old leaves forming a skirt if allowed to remain on the plant. The long flower spike is partly hare. It has been known to grow to 4-5 m (13-16 it), in length but is more usually less than 2-3 m (6-10 ft).

X. macronema has an underground trunk and narrow glossy leaves, up to 1 m (3 ft) long, that are ribbed with sandpapery, rough margins. The short, chunky flowering spike is carried on a tall, slender stem. Flowers are yellow, with long, protruding stamens, and much larger than those of many other species.

X. media generally has an underground trunk, but this may sometimes be up to 80 cm (32 in) above ground. The glossy, green leaves are very narrow and the narrow flowering spike, 30-80 cm (12-32 in) long, is carried on a stalk up to 2 m (6 ft) high.

X. minor is a very small species, with short clumps of slender leaves. The trunks are underground and rarely seen. The flowers are strongly fragrant and may cover a good proportion of the 30-60 cm (12-24 in) long flower spikes.

X. preissii, from Western Australia, has a 5 m (16 ft) high trunk, topped with a rounded tuft of leaves. The cream-coloured flowers are crowded at the top of the 2 m (6 ft) long flower spikes, which extend highabove the crown. They appear in spring.

X. resinosa produces a clump of blue-tinged leaves from its trunk, which is mostly below ground level. The dense flower spike has a dark brown, velvety appearance because of dense hairs on the floral bracts.

Cultivation

In the greenhouse or conservatory, grass trees can be grown in deep containers of sandy, soil-based potting compost, which must be very well drained, as they are prone to root rot. Ensure maximum light, but shield from direct, strong sun. Outdoors grass trees need deep, sandy soil with sharp drainage and full sun to partial shade. Propagate from seed in a warm propagating case. Germination can take up to a year and young growth is generally very slow.

Climate

Zone 10.