Accepted name: Dendrochilum rhombophorum (Rchb.f.) Ames, Orchidaceae 3: 7 (1908)

Subgenus – Acoridium. Section – Acoridium.


 
 

Synonyms

 

Coelogyne rhombophora Rchb.f., Linnaea 41: 116 (1877).

Acoridium rhombophorum (Rchb.f.) Ames, Schedul. Orchid. 5: 1 (1923).

Pholidota rhombophora Rchb.f., Linnaea 41: 117 (1877).

Acoridium whitfordii Rolfe in O.Ames, Orchidaceae 1: 73 (1905).

Dendrochilum whitfordii (Rolfe) Pfitzer & Kraenzl. in H.G.A.Engler (ed.), Pflanzenr., IV, 50 II B 7: 162 (1907).

 

Origin in the Wild

 

Luzon and Mindanao

 

Elevation in the Wild

 

500 - 2500 metres

 

Habitat in the Wild

 

This species has been recorded growing as an epiphyte in mossy forest. Dendrochilum rhombophorum has been recorded from Luzon in Bataan Province along Mamao River in the Mariveles Mountains; Laguna Province in Majayjay and Mount Banahao; Quezon Province at Lucban, Mount Banahao and Mount Binuang; Rizal on Mount Lumutan. On Mindanao this species has been collected in Surigao del Norte Province at Lake Mainit.

 

The Plants Description

 

The pseudobulbs cluster along a short rhizome. The pseudobulbs are shaped obpyriform to fusiform and measure 0.7-1.7cm long and 0.2-0.5cm in diameter. The pseudobulbs are covered by 4-5 cataphylls while they are growing. The cataphylls disintegrate into persistent fibres as the pseudobulbs mature. The leaves are petiolate, the petiole measures 1-7.8cm long. The leaf blades are shaped linear-lanceolate and have obtuse to subacute, sometimes mucronate apices. The leaf blades measure 4.2-14cm long and 0.5-1.3cm wide. The leaves have entire margins and three distinct nerves the two outermost nerves 0.5-1mm from the margin.

 

The Inflorescence

 

The inflorescence is synanthous and free from the subtending leaf at the time of flowering. The peduncle is curved and measures 3.2-17.5cm long. The rachis is pendent and measures 1.2-8.6cm long. The flowers alternate distichously and are spaced 2-3mm apart. There are 2-6 appressed non-floriferous bracts at the base of the rachis. The flowers open from the proximal section of the rachis.

 

The Flowers

 

The colour is recorded as cream to yellow or deep orange, sometimes greenish brown with a brown labellum (Pedersen 1997). Up to 30 flowers grow on an inflorescence (Cootes 2001). The dorsal sepal is shaped obovate to oblong or elliptic and has a rounded to obtuse, sometimes carinate apex. The dorsal sepal measures 1.7-3.1mm long and 0.8-1.7mm wide. The dorsal sepal has an entire margin and is three veined. The lateral sepals are shaped oblique and broadly ovate-elliptic to nearly orbicular and have rounded obtuse or subacute apices. The lateral sepals are slightly carinate and sometimes with finely mucronate apices. The lateral sepals measure 1.7-2.8mm long and 1.2-2mm wide. The lateral sepals have entire margins and are three veined. The petals are recurved, shaped oblique, broadly spathulate and have rounded to shortly acuminate apices. The petals measure 1.7-2.7mm long and 1.3-2.4mm wide. The petals have entire margins and are three veined. The labellum is porrect, concave and entire. The labellum is shaped oblong-obcuneate and has a truncate and apiculate apex, rarely acuminate. The labellum is obscurely auriculate at its base. The labellum measures 1.2-1.7mm long and 0.9-1.4mm wide, is obscurely three veined and glabrous. The lateral margins are quite entire and incurve; the margins sometimes contain a few ocelli. The calli unite into a horseshoe or crescent shape. The column measures 0.4-0.6mm long and is hooded at its apex. The anther cap is sub orbicular from its upper view and rounded-truncate from its front.

 

Herbarium Specimens

 

Possible type

 

AMES

 

Specimen 139137 (photo) (Coelogyne rhombophora)

 

 

Isotype

 

New York Botanical garden (NY)

 

Specimen 39517 (photo) (Acoridium whitfordii)

 

AMES

 

Specimen 64 (photo) (Acoridium whitfordii)

Specimen 1061 (photo) (Acoridium whitfordii)

 

 

Other herbarium specimens

 

National Herbarium Netherlands (L)

 

Specimen L0322718

Specimen L0322719

Specimen L0322720

Specimen L0322721

Specimen L0322722

 

AMES

 

Specimen 98800 (Drawing from type)

 

Scent

 

The flowers have no scent. I have read a forum post that stated the flowers had a strong scent like lemon.

 

Flowering Season

 

Flowering plants have been collected in the wild from March to June. In cultivation they flower in the spring.

 

Culture

 

This species is in cultivation, I have seen plants in Australia, the European Union and The Philippines.

 

Similar Species

 

Dendrochilum marginatum

Dendrochilum philippinense

Dendrochilum macgregorii

Dendrochilum foxworthyi

 

Other Information

 

Henrik Pedersen placed this species in the same group as those outlined above. This species is more closely related to Dendrochilum philippinense and D. macgregorii because of the horseshoe shaped callus on the labellum.

 

Reichenbach described this species in 1877 as Coelogyne rhombophora, Reichenbach stated that it is related to Coelogyne pumila. Pfitzer and Kränzlin transferred the species to Pholidota based on assumption and advice from Reichenbach. Pfitzer and Kränzlin were unable to locate specimens to validate the change and to properly study the plant. Ames transferred the plant to Dendrochilum in 1908 after studying Reichenbach's description and because Reichenbach stated it was closely related to Dendrochilum pumilum.

 

The holotype of Acoridium whitfordii has been destroyed, it was held at Kew.

 

The epithet refers to the oval shaped pseudobulbs.

 

Reference -

 

AMES, Oakes. 1908, Illustrations and studies of the Family Orchidaceae Facsimile 2, Ames Botanical Laboratory, North Easton, Massachusetts, Boston.

 

AMES, Oakes. 1908, Illustrations and studies of the Family Orchidaceae Facsimile 3, Ames Botanical Laboratory, North Easton, Massachusetts, Boston.

 

AMES, Oakes. 1923, New and Noteworthy Orchids Central America and the Philippines, Schedulae Orchidianae, No 5. Massachusetts, Boston.

 

COOTES, Jim. The Orchids of the Philippines, 2001. Timber Press, USA

 

COOTES, Jim. BANKS, David. 1995, The genus Dendrochilum A guide to the species in cultivation, Orchids Australia, AOC

 

PEDERSEN, Henrik. 1997, The Genus Dendrochilum (Orchidaceae) in the Philippines - A Taxonomic Revision. Opera Botanica, Denmark

 

World Checklist of Selected Plant Families. 17 November 2008. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the Internet; http://www.kew.org/wcsp/ accessed 17 November 2008.