A species that is the basis of numerous hybrids and horticultural varieties, Dendrobium bigibbum represents, along with Dendrobium nobile, the most popular taxon in the horticultural trade, both as potted plants and cut flowers. It originates from the tropical area of Australia (North Queensland) and New Guinea.
The species grows on trees and rocks in tropical jungle areas, coastal thickets, near rivers and swamps, as well as in open tropical forests in Queensland, Australia, southern New Guinea, and on a single island in Indonesia.
From a taxonomic point of view, the species was initially described by the renowned botanist John Lindley and published in the periodical Paxton’s Flower Garden.
Currently, there are four varieties recognized by the World Checklist of Plant Families, as follows:
- Dendrobium bigibbum var. bigibbum, which has a white central area on the labellum and lives at low altitudes on the Cape York Peninsula, some of the Torres Strait Islands, and southern New Guinea;
- Dendrobium bigibbum var. compactum, (C.T.White), Peter B.Adams, a lithophilic variety with a restricted distribution at altitudes of 250 m in tropical wet areas;
- Dendrobium bigibbum var. schoederianum (Rchb.f. ex W.Watson), which shows color variability and populates only the Larat Islands in the Tanimbar island group;
- Dendrobium bigibbum var. superbum, Rchb.f., which has the largest flowers among all varieties of Dendrobium bigibbum, but lacks the white central spot on the labellum and populates the area between Cooktown and Mount Molloy.
Dendrobium biggibum is the floral emblem of the Australian state of Queensland. In terms of conservation and protection status, Dendrobium biggibum is listed as a vulnerable species under the Environment Protection and Biodiversity Conservation Act 1999 issued by the Australian Government. The main threats identified for this species are considered to be human settlements and pressures from visitors, such as fire in unmanaged areas and illegal collection.
The known synonyms for this species are: Callista bigibba, Callista phalaenopsis, Callista sumneri, Dendrobium bigibbum f. compactum, Dendrobium bigibbum f. phalaenopsis, Dendrobium bigibbum f. superbium, Dendrobium bigibbum subvar candidum, Dendrobium bigibbum subvar. compactum, Dendrobium bigibbum subvar. superbum, Dendrobium bigibbum var. albopurpuratum, Dendrobium bigibbum var. album, Dendrobium bigibbum var candidum, Dendrobium bigibbum var. macranthum, Dendrobium bigibbum var. phalaenopsis, Dendrobium bigibbum var sumneri, Dendrobium bigibbum var. superbum, Dendrobium lithocola, Dendrobium phalaenopsis, Dendrobium phalaenopsis var. albopurpureum, Dendrobium phalaenopsis var. album, Dendrobium phalaenopsis var. album, Dendrobium phalaenopsis var. chamberlainianum, Dendrobium phalaenopsis var. compactum, Dendrobium phalaenopsis var. dellense, Dendrobium phalaenopsis var. highburyense, Dendrobium phalaenopsis var. hololeuca, Dendrobium phalaenopsis var. lindeniae, Dendrobium phalaenopsis var. rothschildianum, Dendrobium phalaenopsis var. rubescens, Dendrobium phalaenopsis var. schroderianum, Dendrobium phalaenopsis var. schroederianum, Dendrobium phalaenopsis var. splendens, Dendrobium phalaenopsis var. statterianum, Dendrobium phalaenopsis var. thundersleyense, Dendrobium sumneri, Vappodes bigibba, Vappodes lithocola, Vappodes phalaenopsis.
An epiphytic or lithophytic species, with green or sometimes purplish pseudobulbs, ranging from 20 to 120 cm in length and 1.5 – 2 cm in thickness, often with purple growths. Each pseudobulb has between 3 and 5 ovate leaves, 10 – 15 cm long and 3 – 3.5 cm wide. The curved flower spikes, 20 – 40 cm long, bear between 2 and 20 flowers, generally lilac to purple, rarely blue or pink. The resupinate flowers, approximately 2 – 3 cm long and 3 – 7 cm wide, vary in size depending on the variety, with oblong to ovate sepals measuring 2 – 3 cm long and 0.9 – 1.1 cm wide. The dorsal sepal is erect or curved backward, while the lateral sepals are positioned opposite. The petals are ovate, with length and width roughly equal, ranging from 2.5 – 30 cm, and the labellum, 2 – 2.6 cm long and 2 – 2.8 cm wide, is trilobed. The lateral lobes are erect, and the central lobe has 4 – 5 longitudinal ridges as well as a hairy area in the central position. The species blooms from February to July, but horticultural hybrids can bloom abundantly in any season, multiple times a year, depending on environmental conditions.
This species survives in low light areas during winter, but this leads to aborted buds and underdeveloped flower spikes.
In terms of light radiation, Dendrobium biggibum prefers levels of 30,000 – 45,000 lux, with more intense light during the winter. High variations in light intensity and good ventilation are decisive factors for the successful cultivation of this species. In the short term (up to a few weeks), the plant tolerates very low light radiation conditions very well.
The plants love warmth, preferring 29 – 30 ℃ during the day and 20 - 22 ℃ at night in the summer, and 24 – 26 ℃ during the day with 17 – 19 ℃ at night in the winter. Bigibbum can thus be successfully grown outdoors during the warm season, provided that a humidity of 60 – 80% correlated with the ambient temperature is maintained.
Although this orchid can be easily grown mounted on wooden plaques, cork, or bark, its high humidity preferences, especially during the warm period, indicate that cultivation in perforated pots with efficient drainage, on a substrate made of small/medium pine bark granules or specific mixtures, should be preferred. If mounting on plaques is chosen, it is recommended to use a "ball" of sphagnum in the root area for better moisture retention. Repotting should be done during the rest period, towards the end of winter - beginning of spring.
Waterings will be generous in the warm season, but reduced in winter. Dendrobium bigibbum tolerates short-term lack of humidity very well, which allows safe transport of the plants over long distances.
Fertilizations can be done weekly at concentrations of 25% - 50% of the values indicated by the manufacturer on the packaging, preferring a fertilizer with a higher nitrogen content during the growth period, from the beginning until almost the end of summer, and a fertilizer rich in phosphorus from late summer until autumn.
The rest period actually represents just a reduction in watering for a few weeks, after the flowering period. The substrate will be allowed to dry out completely between waterings, but it is recommended to mist the leaves with water and maintain high atmospheric humidity.
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