Afrocarpus dawei / Uganda yellow-wood

Afrocarpus dawei, first described by Otto Stapf (1857–1933) and finalized in 1989 by C.N. Page in New and maintained genera in the conifer families Podocarpaceae and Pinaceae; Notes of the Royal Botanical Garden Edinburgh, vol. 45 no. 2.

Description. Afrocarpus dawei is an evergreen coniferous species of tree which will grow to mature heights of (100 feet (30 m) tall with a 3 foot (100 cm) diameter trunk at breast height, with a long clear bole, a small, flat-topped crown and dense foliage. Bark is dark brown turning gray with age, forming small angular, flaking plates. Twigs are ridged and more or less quadrangular in cross section. Seedling and sapling leaves mostly opposite, linear-lanceolate, up to 6.5 inches (17 cm) long and 0.16 to 0.32 inch (4 - 8 mm) wide, tapering and finely pointed. Adult leaves are smaller, 1.2 to 2 inches (3 - 5 cm) long and 0.08 to 0.16 inch (2 - 4 mm) wide, spirally arranged, with a raised midrib on the lower side, gray-green, the outer quarter of the leaf's length tapering to an acute apex. Pollen cones are produced in bundles of 1's, 2's or 3's, each subtended by whorl of catkin-like, papery bracts, 0.4 to 0.8 inch (10 - 20 mm) long and 0.1 to 0.14 inch (2.5 - 3.5 mm) broad with spirally-arranged, triangular-trullate microsporophylls, 0.04 inch (1 mm) wide, each with two globose pollen sacs. Seed cones grow solitary on scaly twigs axillary to or below foliage leaves, consisting, at maturity, of a single seed completely enclosed by a globose fleshy epimatium 0.9 to 1.2 inches (23 - 30 mm) in diameter, green ripening yellow. Seed is ovoid, 0.48 to 0.6 inch (12 - 15 mm) wide and 0.6 to 0.8 inch (16 - 20 mm) broad, with a 0.08 to 0.16 inch (2 - 4 mm) thick, hard seed coat.

It differs from the other species of Afrocarpus in having a clearly ovoid rather than globose seed (a property shared with the narrow endemic A. mannii, but that species bears its seed in a pear-shaped epimatium) that has a rugose surface and a 0.08 to 0.16 inch (2 - 4 mm) thick seed coat (other species have smooth or verrucose seeds with thinner or thicker seed coats).

Distribution. This species is native to Tanzania (Kagara and Mara provinces) and Uganda; growing at elevations of 3,500 to 3,800 feet (1,100 - 1,200 m) above sea level as a codominant or emergent tree in seasonally flooded forests along rivers east and south of Lake Victoria.

Afrocarpus dawei —foliage and seed cones.
Photo by Daniel Luscombe

Comments