393 NATURE IN SINGAPORE 2009 2: 393–395 Date of Publication: 22 September 2009 © National University of Singapore THE DISTRIBUTION AND STATUS IN SINGAPORE OF BULBOPHYLLUM SESSILE (KOEN.) J. J. SM. (ORCHIDACEAE) A. F. S. L. Lok, W. F. Ang, P. X. Ng, A. T. K. Yee and H. T. W. Tan * Department of Biological Sciences, National University of Singapore 14 Science Drive 4, Singapore 117543, Republic of Singapore ( * Corresponding author: dbsttw@nus.edu.sg ) INTRODUCTION Bulbophyllum sessile belongs to Bulbophyllum section Oxysepalum which is a very widespread section ranging from northern Thailand to the Pacific islands, although this species is the only member of the section in Peninsular Malaysia (Seidenfaden & Wood, 1992). This species has a long, sympodial, slender, hanging rhizome which is highly branched (Fig. 1). The internodes are 3–4 mm long, along which ovoid, 2.5–3.0 mm long pseudobulbs are appressed. The fleshy leaves are 1.8–2.3 by 0.6–0.8 cm with a rounded apex, and a very minute tip, and also narrow base with a very short stalk (to 2 mm long) (Fig. 1). The flowers are solitary and borne at all nodes along the rhizome, and arising from conspicuous sheaths. The flowers appear sessile but are actually borne on very short, 1–2 mm long pedicels. The sepals are pale yellow at the tip, cream at the base and are 3–5 mm long, including a narrow three-angled tip 2.5 mm long. The petals are cream and are 1.0–1.4 mm long. The yellow green lip is similar in length to the petals. This species is distributed from the Andaman Islands, Thailand, through Indochina, Indonesia and New Guinea as well as the Pacific islands. In Peninsular Malaysia, this species is widespread throughout the country in more open situations, such as along forest roads in the lowlands, fruit tree orchards and forest regrowth, where they can be found in considerable masses. In Singapore it is currently classified as nationally critically endangered (Tan et al., 2008), and is probably now found only in the Bukit Timah Nature Reserve (BTNR), and Central Catchment Nature Reserve (CCNR). It was recently observed on abandoned fruit trees in the Lim Chu Kang area on Singapore Island and Pulau Tekong, mainly on durian (Durio zibethinus) and mango (Mangifera indica) trees at Kampong Permatang and Kampong Salabin. The last collection of this species was in Jun.1955 from MacRitchie Reservoir (Table 1) and has not been collected since. It was recently discovered growing together with Bulbophyllum vaginatum on a tree fall along the Nee Soon Pipeline on 28 Feb.2009 (Fig. 2). Table 1. Previous Singapore collections of Bulbophyllum sessile (Koen.) J. J. Sm. deposited in the Herbarium, Singapore Botanic Gardens (SING). S/No. Bar Code No. Collector Collector’s No. Year Locality 1. 0010557 H. N. Ridley s.n. 1889 Kranji 2. 0010551 J. S. Goodenough s.n. 1890 Sungei Murai 3. 0010556 H. N. Ridley s.n. 1892 Chan Chu Kang 4. 0010555 I. H. Burkill, I.H. s.n. 1917 Botanic Gardens 5. 0010554 M. R. Henderson s.n. 1930 Botanic Gardens 6. 0010553 J. Sinclair 40232 1954 MacRitchie Reservoir 7. 0010552 J. Sinclair 40642 1955 MacRitchie Reservoir DETAILS OF COLLECTION On 28 Feb.2009, a fallen tree was discovered along the Nee Soon pipeline (Fig. 2). Initially, the tree’s epiphytes were identified as Bulbophyllum vaginatum but upon closer examination, we found the smaller pseudobulbs of Bulbophyllum sessile growing interspersed with Bulbophyllum vaginatum. As the fallen tree’s crown was dried up with its dead leaves strewn all over the ground, and portions of the bark were flaking away, we were unable to identify the tree upon which Bulbophyllum sessile was growing on. However, the tree’s trunk diameter at breast height was 50 cm, indicating that it was a relatively old tree that grew along the forest edge, near the pipeline.