Dendrobium geminatum

Family : Orchidaceae

Text © Pietro Puccio

 

English translation by Mario Beltramini

 

The species is native to Borneo, Java, Peninsular Malaysia, Peninsular Thailand and Sumatra where it grows on rocks covered by moss or on the trunks of the trees between the 300 and the 1300 m of altitude.

The name of the genus is the combination of the Greek substantives “δένδρον” (dendron) = tree and “βίος” (bios) = life, with reference to the numerous species of the genus living on the trees; the specific name is the Latin adjective “geminatus, a, um” = double, with reference to the inflorescences that generate often coupled in the apical part of the pseudobulb.

The Dendrobium geminatum (Blume) Lindl. (1830) is an epiphytic or lithophytic species with creeping woody rhizome, of 4-5 mm of diameter, and close ovoidal pseudobulbs, grooved, slightly compressed laterally, 2-3,5 cm long and of 0,6-2 cm of diameter, with ramification in various directions with smaller pseudobulbs spaced of 5-15 cm.

The pseudobulbs are provided at the apex of two ovoidal-elliptical to lanceolate leaves with irregularly bilobed apex, 4-12 cm long and 1-2,2 cm broad, coriaceous.

Racemose inflorescences that develop in the same time as the pseudobulb in the apical zone, solitary or more frequently geminate (paired), 6-10 cm long, bearing 3-9 flowers, on a pedicel and ovary about 2 cm long, of 2,5-3 cm of diameter, of cream to pale yellow colour with the lateral lobes of the labellum having brown-purple spottings and median lobe with white margin, long lasting. Lanceolate dorsal sepal with sub-acute apex, 1,3-1,8 cm long and 0,4-0,5 cm broad, lanceolate lateral sepals with sub-acute apex, 1,3-1,5 cm long and 0,7 cm broad, united at the base of the column to form a spur (mentum) about 0,4 cm long.

Linear petals, 1,2-1,6 cm long and 0,2-0,25 cm broad, trilobed labellum, 1-1,2 cm long and 0,6-0,7 cm broad (spread), with erect lateral lobes with rounded margin at the sides of the column and triangular median lobe with acuminate apex; the column is about 0,4 cm long.

It reproduces at amateur level by division, with each section provided of at least 3-4 pseudobulbs.

Species distributed on a vast area of South-East Asia, but little present in cultivation, requires slight shade, intermediate temperatures, with lowest ones not under the 16 °C, high humidity, 75-85 %, and constant ventilation.

The waterings must be regular and abundant, being native to zones with high rainfall well distributed during the whole year, but avoiding the stagnations. It may be mounted on small logs, pieces of bark or rafts covered by sphagnum or cultivated in pots or baskets with a compost based on medium sliced bark fragments.

The species is reported in the appendix II of the CITES (species whose trade is internationally ruled).

Synonyms: Desmotrichum geminatum Blume (1825); Callista geminata (Blume) Kuntze (1891); Sarcopodium geminatum (Blume) Rolfe (1910); Katherinea geminata (Blume) A.D.Hawkes (1956); Epigeneium geminatum (Blume) Summerh. (1957).

 

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