Dendrobium speciosum

Dendrobium speciosum growing on a tree

Dendrobium is one of the largest genera of orchids. Many are lithophytic and epiphytic and so can be grown on rocks or on trees, including Dendrobium speciosum, which is an Australian native sometimes called the king orchid or rock orchid. It was first named in 1804 from a specimen collected by the First Fleet surgeon John White. It forms large clumps, with thick 'pseudobulbs' and leathery leaves. The plant flowers in late winter and early spring, with showy racemes clustered with small perfumed flowers ranging in colour from white to creamy yellow or gold. To see them in the bush in early spring is a wonderful spectacle.

According to a sign I saw in the Royal Botanic Garden, Sydney, 'the starchy stems of this orchid were eaten raw by the Cadigal people, or after roasting them over hot coals'.

Dendrobium speciosum growing on a rock, in the garden of Nancy and Ted Shaw in Sydney

Dendrobium speciosum growing on a rock, in the garden of Nancy and Ted Shaw in Sydney

They can be grown on a rock by sitting them on some orchid compost and propping them up with smaller rocks: they will eventually attach themselves to the main rock. They can also be affixed to a tree using an old stocking partially filled with orchid compost in which to anchor the roots - tie the orchid onto the tree with the ends of the stocking. Eventually it will adhere itself onto the bark. They can also grow in cut-up tree stumps. They can also be wired onto boards. If grown in pots, they need very well-drained orchid medium. They should not be planted directly into soil. Give them water, especially in summer, and some liquid fertiliser occasionally in spring and summer. They need some sun to promote best flowering but should be shaded from the hot afternoon sun. The colour of the flowers can echo cream-coloured Clivia that appear at the same time, and also consorts well with the soft blue flowers of Salvia fallax. Propagate by removing rooted pieces from the clump or by dividing the pseudobulbs into smaller clumps and potting up in orchid mix. The main pest is the dendrobium beetle, which can ruin leaves, new shoots and flowers. Remove them by hand in the early evening. You can flick them into a container with some soapy water at the bottom. Dendrobium can be afflicted by fungal diseases: use Eco Fungicide to control these.