Acoridium tenuibulbum Ames, Blumea, Suppl. 1: 75 (1937).
Origin in the Wild
Luzon and the Visayas?
Elevation in the Wild
Habitat in the Wild
This species has been collected from Luzon's Rizal Province on Montalban. A second collection, its identification uncertain, was collected in the Visayas on Antique on Mount Madia-as.
Pedersen wrote that nothing is known about the habitat of this species (Pedersen 1997). Jim Cootes wrote that this species "grows as an epiphyte, amongst mosses, on tree trunks in quite bright light at elevations over 950 metres" (Cootes 2001)
The Plants Description
The pseudobulbs cluster on a short rhizome and are shaped terete to slenderly semifusiform-terete. The pseudobulbs measure 2.7-9.7cm long and 0.1-0.2cm in diameter. The pseudobulbs are covered by 4-5 cataphylls while they are growing. The cataphylls soon disintegrate into persistent fibres as the pseudobulbs mature. The leaves are petiolate; the petiole measures 1.0-2.9cm long. The leaf blades are shaped lanceolate and have acute apices. The leaf blades measure 7.2-15.2cm long and 1.4-3.1cm wide. The leaves have five distinct nerves on the blade; the two outermost nerves are 1.0-2.0mm from the leaf margin.
The inflorescence is synanthous. The peduncle is suberect to somewhat curved and measures 7.9-15.2cm long. The rachis is pendent and measures 4.4-10.1cm long. The flowers alternate distichously and are spaced 1.5-2.5mm apart. There are 1-3 appressed non-floriferous bracts at the base of the rachis. The flowers open from the proximal section of the rachis or all flowers open more or less at the same time.
Henrik Pedersen wrote (1997) that the flowers are bright yellow (Pedersen 1997). Up to 20 flowers grow on an inflorescence (Cootes 2001). The sepals and petals spread widely. The dorsal sepal is shaped oblong and has an obtuse apex. The dorsal sepal measures 2.9-3.2mm long and 1.2-1.4mm wide. The dorsal sepal is three veined and has an entire margin. The lateral sepals are shaped slightly oblique, elliptic-oblong and have acute apices. The lateral sepals measure 3.0-3.1mm long and 1.5-1.6mm wide. The lateral sepals are three veined and have entire margins. The petals are shaped obovate and have obtuse to rounded apices. The petals measure 2.7-3.0mm long and 1.6-1.7mm wide. The petals are three veined and have entire margins. The labellum is porrect, slightly concave and 3-lobed. The labellum measures 1.5-1.7mm long and 2.1-2.2mm wide. The labellum is three veined, glabrous and has entire margins. The side lobes are erect, shaped obliquely oblong and have rounded apices. The side lobes are equal to the mid-lobe. The mid-lobe is shaped broadly ovate-triangular and has a subacuminate-obtuse apex. There are three calli, the lateral calli are oblongoid and located at the base of the side lobes. The median callus is minute, shaped oblongoid and is located at the base of the hypochile. The column is suberect and measures 0.6-0.7mm long. The column is hooded at its apex. Stelidia and column foot are absent.
Specimen 59 (photo) (syntype)
Specimen 1059 (photo) (syntype)
Other herbarium specimens
Specimen 104048 (photo)
I could find no record
Flowering plants have been collected in the wild during April and May.
This species is found in cultivation outside of herbarium, although not easy to find. I know of plants in cultivation in Europe and Australia.
Be careful of mislabelled plants masquerading as this species
Dendrochilum irigense (see this page for differences)
Dendrochilum pumilum var recurvum (se this page for the differences)
Dendrochilum pumilum var pumilum
Ames and L.O. Williams wrote that they considered this species to be closely related to Dendrochilum mindorense. Henrik Pedersen (1997) wrote that they are similar in many characters but Dendrochilum tenuibulbum is more closely related to Dendrochilum schweinfurthianum, Dendrochilum longibulbum and Dendrochilum pumilum on account of their striated pseudobulbs, thin textured wide leaves, transversely E shaped labellum and an anther cap that is emarginate from the front.
The plant depicted as Dendrochilum pumilum in Jim Cootes and David Banks 1995 Orchids Australia article is Dendrochilum tenuibulbum (Pedersen 1997).
There is no defined holotype since Ames worked from 2 herbarium sheets and never recorded from which one. They have both been designated a syntype status.
The epithet refers to the slender pseudobulbs.
COOTES, Jim. The Orchids of the Philippines, 2001. Timber Press, USA
PEDERSEN, Henrik. 1997, The Genus Dendrochilum (Orchidaceae) in the Philippines - A Taxonomic Revision. Opera Botanica, Denmark
World Checklist of Selected Plant Families. 25 June 2009. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the Internet; http://www.kew.org/wcsp/ accessed 25 June 2009.