Accepted name: Dendrochilum gracile (Hook.f.) J.J.Sm., Recueil Trav. Bot. Néerl. 1: 69 (1904)

Subgenus – Platyclinis. Section – Platyclinis.


 
 
 

Synonyms

 

Dendrochilum heterotum Pfitzer in H.G.A.Engler (ed.), Pflanzenr., IV, 50 II B 7: 103 (1907).

Platyclinis gracilis var. angustifolia Ridl., Mat. Fl. Malay. Penins. 1: 27 (1907).

Dendrochilum tardum J.J.Sm., Bull. Dép. Agric. Indes Néerl. 15: 6 (1908).

Dendrochilum lyriforme J.J.Sm., Brittonia 1: 107 (1931).

 

Origin in the Wild

 

Bali

Flores

Sumba

Sumatra

Java

Peninsula Malaysia

Sarawak

Kalimantan

Sabah

Singapore

Brunei

 

var bicornutum

 

Brunei

Sabah

 

Elevation in the Wild

 

1400 – 1700 meters – Sumatra

1000-1829 metres – Sarawak

300 metres – Sabah

760-1150 metres – Java

 

var bicornutum

 

Brunei – 1300-1500 metres

 

Habitat in the Wild

 

In Sumatra this species has been collected from North Sumatra near Berastagi and West Sumatra from Mount Talang and Bukit Gombak. C.E. Carr collected a plant along the Merek to Sidikalang road.

 

On Peninsula Malaysia this species has been collected in Pahang’s Genting Highlands just below the summit of Gunung Ulu Kali. Further collections have been made in the Cameron Highlands

 

On Java this species has been collected on Gunung Salak, Krawang and Leuwiliang. Jim Comber wrote that this species is common over Java and has a preference for exposed conditions (Comber 1990).

 

On Bali this species has been collected at Bratan Lake, North of Tabanan on Mount Batukaru.

 

Within Sarawak this species has been collected on Gunung Pueh, Mount Penrissen, and the Usan Apau Plateau along the upper Kelyan River, Batu Tiban Hill and along the Bario to Berang trail.

 

Within Sabah this species has been collected along the Tawau River in the Tawau River Forest Reserve.

 

In Kalimantan this species has been collected on Mount Beratus.

 

Within Brunei Dendrochilum gracile var bicornutum has been collected from Gunung Retak and Mount Pagon.

 

Jeffrey Wood described the Bornean habitat as hill and lower montane mossy forest, on sandstone and kerangas forest (Wood 2001).

 

Peter O’Byrne wrote that this species is found along exposed ridge tops and within stunted forest where it receives brighter light (O’Byrne 2001).

 

The Plants Description

 

The pseudobulbs cluster together on a short rhizome. The pseudobulbs are shaped cylindrical or narrowly conical, sometimes ovoid-pyriform or ovoid and measure 1.5-5.0cm long and 0.4-0.7mm wide. The pseudobulbs are covered by 3-4 cataphylls while they are growing. The cataphylls disintegrate into fibres as the pseudobulbs mature. The leaves are petiolate; the petiole measures 0.3-4.5cm long. The leaf blades are shaped narrowly lanceolate-elliptic to elliptic and have obtuse or acute apices. The blades measure 8.6-15.0cm long and 1.1-3.0cm wide. The leaves are thin textured and have 5-9 nerves along their length.

 

The Inflorescence

 

The inflorescence is synanthous and appears from the pseudobulbs before they have developed and at the same time as the leaves. I have found on some of my plants that the inflorescence grows after the leaves have fully expanded. The inflorescence is covered by small black trichomes. The peduncle is suberect to arching and measures 8.0-12.5cm long. The rachis is quadrangular in cross section, pendent and measures 8.0-12.7cm long. There are up to 6 or no non-floriferous bracts at the base of the rachis. The flowers open from the proximal section of the rachis.

 

The Flowers

 

I have counted between 30 and 34 flowers on an inflorescence on my own plants. Jim Comber wrote that the inflorescence bears about 35 flowers. The longest the flowers have stayed open on my own plants is 40 days, the longest on any Dendrochilum in my collection. The flowers are greenish brown, pale green or yellow-green and have brown or blackish brown vertical markings on the labellum. The sepals and petals either open widely or are slightly incurved and are sometimes sparsely papillose at their bases. The dorsal sepal is shaped narrowly elliptic or ovate-elliptic and has an acute apex. The dorsal sepal is slightly concave and sometimes with a few papillae at its base. The dorsal sepal measures 5.8-8.7mm long and 1.6-2.1mm wide. The dorsal sepal is three veined and has an entire margin. The lateral sepals are shaped narrowly obliquely ovate-elliptic and have acute apices. The lateral sepals are slightly concave and sometimes have a few basal papillae. The lateral sepals measure 5.1-8.5mm long and 1.8-2.4mm wide. The lateral sepals are three veined and have entire margins. The petals are shaped narrowly obliquely elliptic and have acute apices. The petals measure 5.0-8.2mm long and 1.1-2.0mm wide. The petals are three veined and often have minutely erose margins. The labellum is stipitate to the column by a short claw, porrect, recurved above the base and 3-lobed. There are three prominent veins on the labellum. The labellum measures 3.5-7.7mm long and 1.5-4.7mm wide. The side lobes are shaped linear to narrowly oblong-triangular and have acuminate apices that point outwards. The upper margins of the side lobes are serrate to laciniate. The mid-lobe is shaped ovate, suborbicular to subrhombic or subspathulate and has a shortly apiculate to subacute apex. The mid-lobe margin is irregular to erose. There are two keels that are joined at the base. The keels terminate just beyond the base of the labellum. The median nerve is sometimes elevated and joins the two lateral keels to form an M shape basally. Dendrochilum gracile var bicornutum have keels that have basal thorn like projections. The column is incurved and measures 2.9-4.0mm long. The column foot is prominent. The apical hood is elongated into an ovate shaped hood and has an entire or irregularly bidentate, to 5-dentate margin. The stelidia grow upwards from the centre of the column and are slightly shorter than the column apex. The stelidia measure 1.7-2mm long and are shaped linear-subulate, falcate with acute apices. The stelidia are slightly twisted.

 

Herbarium Specimens

 

Holotype

 

I could not locate the holotype

 

Isotype

 

Royal Botanic gardens Kew (K)

 

Specimen K000079107 (photo)

Specimen 60690.000 (var bicornutum)

 

New York Botanical Garden (NY)

 

Specimen 8740 (Photo) (Dendrochilum lyriforme)

 

National Herbarium Netherlands (L)

 

Specimen L0056510 (photo) (Dendrochilum lyriforme)

 

Other herbarium specimens

 

National Herbarium Netherlands, Leiden (L)

 

Specimen L0269590

Specimen L0269591

Specimen L0269592

Specimen L0269593

Specimen L0269594

Specimen L0269595

Specimen L0269596

Specimen L0269597

Specimen L0269598

Specimen L0322494

Specimen L0322536

Specimen L0322537

Specimen L0322495

Specimen L0322496

Specimen L0322497

Specimen L0322498

Specimen L0322499

Specimen L0322500

Specimen L0322501

 

Royal Botanic Gardens Kew (K)

 

Specimen 31330.000

Specimen 74036.00

Specimen 39328.000

Specimen 77464.000

Specimen 41355.000

Specimen 43171.000

Specimen 43168.000

Specimen K000079155 (photo)

Specimen 43199.000

Specimen 61444.000

Specimen 60422.000

Specimen K000079143 (photo) (Dendrochilum heterotum)

Specimen 60423.000 (var bicornutum)

Specimen 60691.000 (var bicornutum)

 

Bogor (BO)

 

Scent

 

Yes a sweet and pleasing scent, prevalent during the day.

 

Flowering Season

 

In my own cultivation, in the UK, this species has flowered during the later part of summer.

 

On Peninsula Malaysia flowering plants have been collected in the wild during January, March, April, and August.

 

Flowering plants have been collected on Sumatra during October and November.

 

Flowering plants have been collected on Java during September and October.

 

Flowering plants have been collected on Flores during May.

 

Flowering plants have been collected on Bali during June and July.

 

Flowering plants have been collected on Sumba during July.

 

Flowering plants have been collected in Sarawak during March and from August to December.

 

Flowering plants have been collected in Kalimantan during July.

 

Flowering plants have been collected in Sabah during November.

 

Flowering plants of Dendrochilum gracile var bicornutum have been collected in the wild during January, March, April and December.

 

Culture

 

This species is often found in cultivation.

 

I have found that this species like brighter light than other Dendrochilum. I don’t fertilize my plants as a general rule but I find that I get more inflorescences on this species if I weakly fertilize as the new growths appear. It is important that this species gets constant air movement as the new growths are prone to rotting and browning off from the leaf apex.

 

Similar Species

 

Dendrochilum truncatum (for differences please check this page)

Dendrochilum papillosum (for differences please check this page)

Dendrochilum edanoi

Dendrochilum flos-susanne (see this page for the differences)

Dendrochilum longirachis

Dendrochilum megalanthum

Dendrochilum uncatum var. uncatum

Dendrochilum uncatum var longispicatum

 

Other Information

 

This species shows considerable variety over its range. There are bronze leaved varieties from Peninsula Malaysia. Dendrochilum lyriforme was named by J.J. Smith and said to differ by its laxer inflorescence and up to 6 non floriferous bracts at the base of the rachis. Jeffrey Wood could see no other differences between the types and added Dendrochilum lyriforme as a synonym of Dendrochilum gracile (Wood 2001).

 

Dendrochilum tardum is only known from the type. Jeffrey Wood could see no discernable differences to justify it being a species and added it as a synonym of Dendrochilum gracile (Wood 2001).

 

The variety Dendrochilum gracile var. bicornutum has thorn like basal projections on the keels. Dendrochilum gracile var. bicornutum has only been recorded from Mount Pagon in Brunei and Mount Trus Madi in Sabah at elevations between 1300-1500 metres. Its habitat is upper montane swamp forest on sandstone (Wood 2001). Dendrochilum gracile var. bicornutum has been collected in flower during January, March, April and December.

 

The epithet refers to the slender and graceful habit of the plant.

 

Reference

 

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

 

COMBER, J.B. Orchids of Java, 1990, Royal Botanic Gardens Kew, UK

 

COMBER, J.B. Orchids of Sumatra, 2001, Royal Botanic Gardens Kew

 

O’BYRNE, Peter. 2001, An A to Z of South East Asian Orchids, The Orchid Review Vol 109 n 1241 Sept-Oct p280-285

 

PEDERSEN, Henrik. 1995, Thirteen new species of Dendrochilum (Orchidaceae), a new record from Burma, and a checklist of the genus in East Malesia. Nord. J. Bot 15:381-402. Copenhagen, Denmark.

 

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

 

World Checklist of Selected Plant Families. 25 September 2008. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the Internet; http://www.kew.org/wcsp/ accessed 25 September 2008.