Buxaceae are a small family of mostly an evergreen shrub to medium-sized trees. Currently, the family comprises about 120 species within 6 accepted genera: Buxus L., Didymeles Thouars, Hapthanthus Goldberg & C.Nelson, Pachysandra Michx., Sarcococca Lindl. and Styloceras Kunth ex A.Juss. (POWO, 2022).
Of the 6 genera, the Buxus or commonly called boxwood is the largest genera consisting of over 100 species distributed worldwide mainly in America, Europe, Africa and Asia (POWO, 2022). In Malaysia, there are four taxa recorded with three in Peninsular Malaysia that are restricted to limestone areas namely Buxus cochinchinensis var. holttumiana (Hatus.) Julius, B. malayana Ridl., B. rupicola ridl. and one in Sabah, B. rolfei S.Vidal (Julius, 2015).
Buxus rupicola is known as one of the rare and endemic species in Peninsular Malaysia. The species is only known from Kedah where it is found in a few islands in Langkawi (Pulau Dayang Bunting and Pulau Simpang Tiga Kechil) (Kiew et. al, 2017). Due to its restricted distribution, the conservation status for this species has been assessed as Vulnerable.
The species epithet is derived from the Latin words ‘rupes’ meaning rock and ‘icola’ meaning dweller, which refers to the plant’s habitat because it typically grows on limestone cliffs between 20 to 150 meters above sea level.
This medium-sized bushy shrub can grow up to 1.5 – 3.0 m tall. It has many spreading branches and twigs with pale, corky bark. The twigs are minutely pubescent when young and glabrescent with age. It has oblanceolate-elliptic and leather-like texture leaves with very short petiole. The leaves are pale brownish to orange when young and turn pale greyish green when mature.
B. rupicola is a monoecious plant where male and female flowers are present on the same plant. This species has 6 – 11 mm long inflorescences. Both male and female flowers species have greenish tepals, covered with white, thick short hair on the outside and smooth inside. Male flowers species have 6–7 greenish, well-spaced greyish pedicels (Julius, 2015).
According to Julius (2013), this species can be differentiated from the other two Peninsular Malaysian species by its inflorescences (lax flowered with 6–8 male flowers and longer pedicels) and its small, pale greyish green leaves.
