Foliage buds 2-4 mm long, primary scales erect. Juvenile leaves up to at least 9 by 1.3 cm, acute or more or less rounded at the apex. Adult leaves linear, 4-7 cm (or as little as 2.5 cm on short side branches) by 5-10 mm, broadly acute or more usually rounded at the apex, sometimes with a small blunt apiculus, narrowing more or less abruptly at the base to a 2-3 mm petiole, slightly revolute; midrib above a distinct ridge 0.3 mm wide and 0.2 mm high
Seed and Fruit
Seed-bearing structure on a 4-6 mm peduncle; foliola c. 1.5 mm long and early caducous; receptacle 12-15 mm long, reported to be red when mature. Seed with its covering 9-10 (including a small crest) by 6-7 mm. ... [O]ften confused with P. polystachyus because of a similar habitat and similar sized leaves. The leaves of P. costalis are slightly revolute while those of P. polystachyus are not' (de Laubenfels 1988).