Dendrobium gracilicaule is native to Eastern Australia. The natural habitat stretches from Kiama in the state of New South Wales to the north as far as Cairns near the Bloomfield River in Queensland. These plants usually grow on trees in shady forests, but sometimes they are found on rocks, in coastal shrubs and in open forest spaces, often in full sun. In the northern part of the habitats, they are found only in the mountains and on the plateaus.
I. Appearance and Characteristics
Dendrobium gracilicaule, commonly known as the blotched cane orchid or yellow cane orchid, is an epiphytic or lithophytic orchid in the family Orchidaceae.
Dendrobium gracilicaule was first formally described in 1859 by Ferdinand von Mueller and the description was published in Fragmenta phytographiae Australiae from a specimen collected by William Hill near Moreton Bay. The specific epithet (gracilicaule) is derived from the Latin words gracilis meaning “slender” or “thin” and caulis meaning “stem” or “stalk”.
There are two varieties of this orchid:
- Dendrobium gracilicaule var. gracilicaule – the blotched cane orchid which has large reddish brown blotches on the back of the flowers and grows on trees or rocks usually in rainforest between Mount Fox in Queensland and the Hawkesbury River in New South Wales.
- Dendrobium gracilicaule var. howeanum Maiden – the yellow cane orchid, which lacks spots on the back of the flowers and grows in humid forests on Lord Howe Island, the Kermadec Islands, Fiji, New Caledonia and Vanuatu.
Dendrobium gracilicaule is an epiphytic or lithophytic herb that has cylindrical, yellowish green pseudobulbs 40–100 cm (20–40 in) long and 4–13 mm (0.2–0.5 in) wide, each with between three and seven leaves on the top. The leaves are thin, dark green, 70–130 mm (3–5 in) long and 20–40 mm (0.8–2 in) wide.
The flowering stem is 50–150 mm (2–6 in) long and bears between five and thirty, often drooping flowers. The flowers are cream-coloured to yellow or greenish, 10–16 mm (0.39–0.63 in) long and wide, in one variety with large reddish blotches on the back. The sepals are 7–10 mm (0.3–0.4 in) long, 3–4 mm (0.12–0.16 in) wide and are relatively thick and fleshy.
The petals are 7–10 mm (0.3–0.4 in) long, 3–4 mm (0.1–0.2 in) wide. The labellum is 7–10 mm (0.3–0.4 in) long, 5–6 mm (0.20–0.24 in) wide and has three lobes. The side lobes curve upwards and the middle lobe is kidney-shaped and has three wavy ridges. Flowering occurs between July and September.
II. How to Grow and Care
Sunlight
Dendrobium gracilicaule needs a light level of 25000-45000 lux. The light level should be as high as the plant can tolerate without burning the leaves. The plants growing in full sun, exposed to high levels of light are smaller, while those growing in more shadowy conditions are larger.
Temperature
The average temperature of the summer day is 26 ° C, the night 16-17 ° C, which gives a daily difference of 9-10 ° C. The average temperature of the winter day is 16-21 ° C, and the winter night is 6-9 ° C, giving a daily difference of 11-12 ° C.
Humidity
The Yellow Cane Orchid needs the humidity of 60-65% throughout the year. You need to ensure strong air movement throughout the year.
Watering
Precipitation is moderate in summer and autumn, but the winter is a bit drier. In cultivation, the delicate roots of Dendrobium gracilicaule are easily damaged by excessive watering. They must dry out between waterings, in addition, excellent ventilation is required.
Substrate, growing media and repotting
Dendrobium gracilicaule grows best on rootstocks made of cork or other hardwood. Mounted plants require daily watering and high humidity in the summer. If they are grown in pots, ceramic pots are better, they should be as small as possible and a fast-drying substrate and perfect drainage are recommended. Repotting is best done just after flowering.
Fertilizing
It is recommended to apply a 1/4-1/2 dose of orchid fertilizer weekly. High-nitrogen fertilizer is beneficial from spring to mid-summer, and then use high-phosphorus fertilizer. The plants should be stimulated to the maximum growth in summer.
Rest period
Dendrobium gracilicaule is often considered difficult to grow. The clear seasons are particularly important for plants. A cold, dry winter is very important. In winter, nighttime temperature should not be below 2 ° C. From mid-autumn until the emergence of new growths in spring, the amount of water should be significantly reduced. When new growths reach maturity in autumn, the fertilization should be reduced or eliminated.
