Agathis flavescens is a small to medium-sized tree, which can grow up to 21 m tall and about 50 cm in diameter. It is commonly known as Tahan Agathis (Lim & Thomas, 2011). The inner bark is reddish-brown. The leaves are glossy yellow to green, opposite, and measured around 3-5.5 cm long x 2.5-3 cm wide. When drying, the leaves become yellowish-brown to dark reddish-brown above and light yellowish brown to dark reddish-brown beneath. Compared to other species, the apex of this tree is rounded. The mature pollen cones are less than 1.2 cm wide. The microsporophyll is helmeted-shaped. The seed cones are dark reddish-brown to black and ovoid in shape. The seeds are flattened and ovoid in shape, measuring around 6 x 3 mm.

The genus derived from a Greek word, agathis means a clew, corner of a sail, and this may refer to the leaf shape; meanwhile, the species epithet derived Latin, flasvescens meaning turning yellow, which refer to the foliage.

This tree is endemic to Peninsular Malaysia, which occurs in Gunung Tahan and Gunung Rabong. It is restricted to the lower and upper montane forest on quartzite-derived soils at 1,200-2,100 m a.s.l. (Lim, 2010). It is listed as a vulnerable species in the IUCN Red List because the total population is estimated to be less than 1,000 mature individuals. However, its habitats are in Totally Protected Areas and no decline has been recorded to date (Lim & Thomas, 2011).