Dimorphorchis

Dimorphorchis is a genus of flowering plants from the orchid family, Orchidaceae. It contains 9 species, which are native to Papua New Guinea, the Philippines, Indonesia, Malaysia, Solomon Islands, and Brunei.^[2] It is remarkable for its two flower morphs present on the same plant.^[3]

Dimorphorchis
Dimorphorchis rossii
Botanical illustration of Dimorphorchis lowii
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Order:	Asparagales
Family:	Orchidaceae
Subfamily:	Epidendroideae
Tribe:	Vandeae
Subtribe:	Aeridinae
Genus:	Dimorphorchis Rolfe
Type species
Dimorphorchis lowii (Benth. & Hook. f.) Rolfe[1]
Synonyms[2]
Arachnopapua R.Rice Lowianthus Becc.

Description

D. rossii distal flower. At Sakuya Konohana Kan.

Vegetative characteristics

Its species are epiphytic, monopodial herbs with large, pendulous,^[4] spreading, or erect^[5] up to 200 cm long stems.^[6] The basal part of the stem bears roots.^[5] The distichously arranged,^[5][4] coriaceous,^[4] linear^[5] up to 70 cm long leaves^[6] have an unequally bilobed to acute apex.^[5]

Generative characteristics

The long,^[7] glabrous^[5] or pubescent,^[5][7] pendent or erect, racemose or paniculate,^[5] up to 3 metres long inflorescences^[6] bear dimorphic (heteranthous)^[3][6] or not dimorphic,^[5] bisexual flowers.^[6][8] The 2-3 flowers closest to the base of the inflorescence are strongly fragrant, slightly smaller, and of a different colour compared to the rest of the flowers, which are unscented and have wavy petals.^[6] The four pollinia with an elliptic viscidium are grouped in two pairs.^[5] It is unknown how the genus is pollinated.^[5][6]

Taxonomy

It was published by Robert Allen Rolfe in 1919^[3][9] with Dimorphorchis lowii (Benth. & Hook. f.) Rolfe as the type species.^[1]

Species

It has nine species:^[2]

• Dimorphorchis beccarii (Rchb.f.) Kocyan & Schuit.
• Dimorphorchis breviscapa (J.J.Sm.) Kocyan & Schuit.
• Dimorphorchis celebica (Schltr.) Ormerod
• Dimorphorchis graciliscapa (A.Lamb & Shim) P.J.Cribb
• Dimorphorchis lowii (Lindl.) Rolfe
• Dimorphorchis lyonii (Ames) Ormerod
• Dimorphorchis rohaniana (Rchb.f.) P.J.Cribb
• Dimorphorchis rossii Fowlie
• Dimorphorchis tenomensis (A.Lamb) P.J.Cribb

Phylogenetic relationships

Within the subtribe Aeridinae, it is the sistergroup to Thrixspermum.^[7]

Etymology

The generic name Dimorphorchis references the characteristic two flower morphs preset within the same plant.^[3]

Ecology

Habitat

It can grow as a lithophyte or epiphyte in rainforests.^[10]