Dendrobium convexum

Dendrobium convexum, commonly known as the piggyback orchid,^[2] is an epiphytic orchid in the family Orchidaceae. It has a creeping, brittle root, erect pseudobulbs with a single leaf on the top and one or two cream-coloured, short-lived flowers with a red and yellow labellum. It is native to Southeast Asia, New Guinea and tropical North Queensland, Australia.

Piggyback orchid
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Order:	Asparagales
Family:	Orchidaceae
Subfamily:	Epidendroideae
Genus:	Dendrobium
Species:	D. convexum
Binomial name
Dendrobium convexum (Blume) Lindl.[1]
Synonyms[1]
Desmotrichum convexum Blume Callista convexa (Blume) Kuntze Ephemerantha convexa (Blume) P.F.Hunt & Summerh. Flickingeria convexa (Blume) A.D.Hawkes Abaxianthus convexus (Blume) M.A.Clem. & D.L.Jones

Middle diagram is Dendrobium convexum

Description

Dendrobium convexum is an epiphytic herb with a brittle root about 3 mm (0.1 in) thick creeping over the surface of rough-barked trees. Shiny pseudobulbs 40–50 mm (1.6–2.0 in) long and 8–10 mm (0.31–0.39 in) wide arise at well-spaced intervals along the root, each on a thin stalk about 10 mm (0.4 in) long. There is a single dark green leaf 50–80 mm (2–3 in) long and 15–18 mm (0.59–0.71 in) wide on the end of the pseudobulb. One or two cream-coloured flowers 12–15 mm (0.47–0.59 in) wide appear at the base of the leaf on a pedicel 5 mm (0.2 in) long. The dorsal sepal is 5–7 mm (0.20–0.28 in) long and about 4 mm (0.16 in) wide. The lateral sepals are 3–4 mm (0.12–0.16 in) long and the petals are linear, 5–6 mm (0.20–0.24 in) long and about 1 mm (0.04 in) wide. The labellum is yellow with a red centre, about 11 mm (0.43 in) long and 4 mm (0.2 in) wide and has three lobes. Flowering occurs sporadically and the flowers open for less than a day.^[2][3][4][5]

Taxonomy and naming

The piggyback orchid was first formally described in 1825 by Carl Ludwig Blume who gave it the name Desmotrichum convexum.^[6] He published the description in his book Bijdragen tot de flora van Nederlandsch Indië.^[6][7] In 1831, John Lindley changed the name to Dendrobium convexum.^[8] The specific epithet (convexum) is a Latin word meaning "arched outward" or "protuberant".^[9]

Distribution and habitat

Dendrobium convexum grows in mangroves, humid areas of scrub, forest and rainforest mainly on rough-barked trees. It occurs in Malaysia, Thailand, Indonesia, New Guinea and on the Cape York Peninsula as far south as Innisfail, Australia.^[2][3][4]