Dendrobium Speciosum - the Rock Lily - Tar-Beri

Dendrobium speciosum is native to a vast section of Australia ranging from Mallacoota (37°33'S) south-east Victoria to the tropical conditions up past Cairns (16°57′S).

It is known as "Tar-Beri" to the aborigines, and "Rock Lily" or "King Orchid" to other Australians. It blooms extraordinarily flower-laden plumes, like bushy fox tails, of fragrant, creamy white flowers. The showy flowers grow in long racemes on straight or slowly arching, long, starchy stems with over 100 small sweetly fragrant flowers per stem from August to October in Australia, or February to April in the Northern hemisphere. Their color varies from white to creamy yellow. The white labellum is covered with purple dots and veined with red and purple.

There are two to five thick, leathery leaves originating from the top of each pseudobulb. These leaves can remain on the plant for up to 12 years. The erect or curved pseudobulbs are rather large, up to 45 cm long. They are thickest at their base (5 to 7 cm), and often taper towards the apex (3 cm).

Cultivation

This is an orchid that thrives on low-medium humidity, bright to very bright light and an open well drained pot with orchid compost.

A constantly moist root system is important, as in natural cliff faces they live on weep moisture constantly. Water all year round in moderation.I n the wild, it is nearly always growing on granite cliff faces or boulders in open grassy paddocks. The speciosum's root systems are often covered with a blanket of moist ferns and mosses.

These orchids are great growers and in time can get huge!

Very bright, open, breezy positions in the growing season seem to be the key to mass blooming.

Speciosums can be acclimatised to take 100% full-sun if slowly positioned into brighter and brighter light from late winter onwards. It is in these full sun positions that they will bloom annually without fail.

It is extraordinarily tough, hardy and drought tolerant. It can tolerate short periods of temperatures near frost to over 45°c without severe damage.

So, growing dendrobium speciosum is simple. Avoid frosts, unaccustomed hot sun, too much shade (make sure you can see a shadow when placing hand above foliage) and temperatures above 36c if possible. Anywhere that has similar conditions to south-eastern Australia will be able to grow this orchid with ease. In the UK the orchid will thrive in full sun outside during summer with overwintering in a cool greenhouse.

Pots should always have excellent drainage and not be too large in comparison to the orchid. As they are vigorous growers, re pot annually.  The compost should be open well drained and have about 25% rock present.

They are virtually free of pests, as their foliage is beautifully thick and sturdy. 

Some subgroups.

Because dendrobium speciosum is found over such a vast region, botanists have broken the species apart into many subspecies or varieties. The naming of these groups is subject to regular review and change!

The far Southern form known as dendrobium speciosum var speciosum is the easiest to grow (and most tolerant of low temperature). 

The deepest colour forms are unusual variants of speciosum var grandiflorum, these may be rich golden yellow, and sometimes in full sun almost a golden orange.

Generally a good rich daffodil yellow is to be expected. In nature most clones are a pale lemon or yellow/cream in colour, very rarely are true clear whites seen.

The shortest caned forms are the pedunculatum forms from furthest north Queensland. They may have fully mature blooming sized canes at only 3" tall!

The Hillii variety tends to produces clawed tiny blooms in pale creams on disproportionately giant canes, which is great in nature but not usually preferred by growers.