3rd Edition Of Plant Science and Molecular Biology World Conference 2026

Abstract

Arundina graminifolia (D.Don) Hochr., commonly known as the bamboo orchid, is one of the most widespread orchid species in Peninsular Malaysia. The genus Arundina is monotypic and contains only one recognised species, A. graminifolia. Despite this, the species exhibits considerable morphological variation, particularly in its floral traits, which has led to taxonomic confusion within the species complex. This species is commonly found growing along open roadsides that receive full sunlight. The purple-flowered form is typically associated with montane areas such as Cameron Highlands and Genting Highlands, where it grows on well-drained and relatively fertile mountain soils along open slopes or roadside banks. In contrast, the white-flowered form is often found in rocky habitats near streams or dam areas, growing on or between wet rocks with flowing water in shallow and nutrientpoor substrates. The main objective of this study was to clarify the taxonomic status of A. graminifolia by comparing morphological characteristics and chromosome numbers across different populations in Peninsular Malaysia. Samples were divided into two groups based on flower colour: purple-flowered and white-flowered A. graminifolia. Purple-flowered samples were collected from Cameron Highlands and Genting Highlands, while whiteflowered samples were obtained from Gunung Jerai and Hentian R&R Bintang Hijau Sungai Rui. The macro- and micromorphological characteristics of the flowers were examined in detail. For chromosome analysis, root tips from each population were collected, pre-treated and squashed on glass slides for microscopic observation. Well-spread chromosomes were photographed and used for chromosome counting. The results showed that the main visible difference between the two groups was flower size. Purple-flowered samples had a larger flower diameter (x̄= 9.3 cm, n = 5) compared to white-flowered samples (x̄= 6.6 cm, n = 5). However, both groups displayed similar floral characteristics, including elliptic-oblong dorsal and lateral sepals, elliptic petals, an obcordate labellum, an arched column with a slightly winged column cap, a white anther cap with two sets of four-lobed pollinia, and three keels on the midlobe of the labellum extending from the base towards the flower opening, with the middle keel being shorter. In addition, the chromosome number of purple-flowered A. graminifolia ranged from 30 to 34, whereas the white-flowered plants ranged from 22 to 24. Although previous studies reported chromosome numbers between 20 and 40 for this species, no distinction was made between purple- and white-flowered forms. This comparative study of morphological characteristics and chromosome numbers across populations in Peninsular Malaysia provides new insights into the taxonomic delimitation of the Arundina graminifolia species complex.