Accepted name: Dendrochilum exasperatum Ames, Orchidaceae 6: 50 (1920)

Subgenus – Platyclinis. Section – Cruciformia.


 
 
 

Synonyms

 

None

 

Origin in the Wild

 

Sabah and Sarawak

 

Elevation in the Wild

 

900-2500 metres

 

Habitat in the Wild

 

The type was collected in Sabah on Mount Kinabalu on the Marai Parai Spur. The only place in Sarawak this species has been collected is on Mount Dulit in the Marudi District.

 

Elsewhere in Sabah this species has been collected in Tenom District at Sapong and Mount Anginon. Within the Sipitang District it has been collected on Mount Lumaku and along the Rurun River. This species has been collected from many locations on Mount Kinabalu and also on Mount Alab within the Crocker Range.

 

This species is an epiphyte and has been known to grow as a terrestrial. Jeffrey Wood described the habitat as lower montane ridge forest on sandstone soils, mossy forest (Wood 2001). This species has also been recorded growing fully exposed in sunlight and in 60& sunlight high up in the forest canopy. Todd Barkman found this species growing on the trunk of a Leptospermum javanicum.

 

The Plants Description

 

This pseudobulbs cluster on a short rhizome. The rhizome can reach a length of 8cm long. The pseudobulbs are shaped narrowly cylindrical or fusiform. The pseudobulbs measure 1-6cm long and 0.4-0.6cm in diameter. The pseudobulbs are covered by 4 cataphylls while they are growing. The cataphylls disintegrate into non-persistent fibres as the pseudobulbs mature. The leaves are petiolate; the petiole measures 0.5-4cm long. The leaf blades are shaped oblong-elliptic to elliptic and have obtuse to minutely mucronate apices. The leaf blades measure 5-16cm long and 1.5-3.5cm wide. There are 7 distinct nerves on the blade.

 

The Inflorescence

 

The peduncle is suberect and measures 5-15cm long. The rachis is curved and measures 8-25cm long. The rachis is quadrangular in cross-section. The flowers alternate distichously and are spaced 2-4mm apart. There is 1 non-floriferous bract at the base of the rachis.

 

The Flowers

 

The flowers are coloured either greenish with a brown labellum or reddish-ochre with a darker red labellum which is pink at the mid lobe apex, or white or greenish-yellow with a triangular spot at the base of each mid-lobe. The dorsal sepal is shaped narrowly oblong-elliptic and has an acute apex. The dorsal sepal measures 6mm long and 1.5mm wide. The dorsal sepal has entire margins and is 3-veined. The lateral sepals are shaped obliquely oblong-elliptic, somewhat falcate and have acute apices. The lateral sepals measure 4.6-5mm long and 1.7-1.8mm wide. The lateral sepals have entire margins and are 3-veined. The lateral sepals can sometimes overlap at their apices. The petals are shaped narrowly elliptic and have acute, somewhat falcate apices. The petals measure 4-5mm long and 1.1-1.5mm wide. The petals have entire margins and are 2 or 3-veined. The labellum is obscurely 5-lobed. The labellum measures 2.5-3mm long and 1.8-2mm at its widest point. The side lobes are flat, very small and shaped triangular with rounded to truncate apices. The mid lobe is shaped cruciform, and has erect side lobules that are shaped oblong with rounded to truncate apices. The median lobule is decurved, cuspidate, shaped triangular and has an acuminate apex. The margins on the labellum are entire. There are 2 keels that join to form a U shape near the base of the labellum; the keels terminate at the base of the side lobules. The column is slender and measures 2.8-3mm long. The column foot is absent. The apical hood is elongated and shaped oblong-triangular and has an obtuse to acute apex. The apical hood has entire margins. The stelidia grow from the base of the column and do not exceed the column apex. The stelidia are shaped ligulate and have obtuse apices that are hooked.

 

Herbarium Specimens

 

Holotype

 

AMES

 

Specimen 48120 (photo)

 

Isotype

 

NA

 

 

Other herbarium specimens

 

National herbarium Netherlands, Leiden (L)

 

Specimen L0322473

Specimen L0322474

Specimen L0322475

Specimen L0322476

 

Royal Botanic Gardens, Kew (K)

 

Specimen 61473.000

Specimen 60415.000

Specimen K000078185

Specimen 50998.000

Specimen 60414.000

 

Scent

 

The flowers are recorded as having ‘little or no scent’. Jeffrey Wood wrote that the flowers are scented or unscented (Wood 1997).

 

Flowering Season

 

Flowering plants have been collected in the wild during April and from September to January.

 

Culture

 

I do not think this species is in cultivation.

 

Similar Species

 

Dendrochilum gibbsiae

 

Other Information

 

Jeffrey Wood wrote that this species is similar to Dendrochilum gibbsiae because of the similar labellum and column. This species differs from Dendrochilum gibbsiae, by the shorter and broader leaves with more obtuse apices. The flowers are larger and the side lobes less developed (Wood 1997).

 

Ames described the flowers as yellow in the original description. Ames also wrote that Dendrochilum exasperatum is almost a counterpart of D. quinquelobum (D. gibbsiae) but is larger.

 

The epithet refers to the Latin word exasperatus which means covered by small short hard points.

 

Reference

 

AMES, Oakes. 1920, Illustrations and studies of the Family Orchidaceae Facsimile 6 The Orchids of Mount Kinabalu British North Borneo, Ames Botanical Laboratory, North Easton, Massachusetts, Boston.

 

BEAMAN, Teofila, WOOD, Jeffrey, BEAMAN, Reed, BEAMAN, John. 2001, Orchids of Sarawak, Natural History Publications Borneo, Kota Kinabalu, Malaysia.

 

WOOD, Jeffrey. 1997, Orchids of Borneo volume 3. The Sabah Society, Kota Kinabalu, Malaysia.

 

WOOD, Jeffrey. Dendrochilum of Borneo, 2001. Natural History Publications (Borneo), Malaysia.

 

World Checklist of Selected Plant Families. 15 January 2009. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the Internet; http://www.kew.org/wcsp/ accessed 15 January 2009.