Libocedrus bidwillii

Detailed description

Tree 25–(30) m tall and 1.0–1.5 m d.b.h., or a shrub in open conditions, evergreen, monoecious. Bark thin, scaly, greyish-brown, exfoliating in longitudinal strips. Branches long, spreading or ascending, arranged in dense tufts above each other, forming a pyramidal crown in young trees, conical or irregular with a clear bole in old trees. Foliage flattened sprays in young trees, in old trees more irregular and ascending, ultimate branchlets subopposite to alternate, 5–40 mm long, entirely covered with leaves, changing with age of plant from flattened to ± quadrangular, persistent. Leaves decussate, on lateral branchlets, short, decurrent, imbricate, dimorphic in young trees, facials small, rhombic, 1.5–2.0 × 1.0 mm, apiculate to acute, appressed, partly covered at base by larger 2.0–6.0 × 1.5–2.5 mm, divergent, bilaterally flattened, slightly curved laterals with entire margins and free apices, leaves on mature trees smaller, nearly monomorphic; amphistomatic, stomata on facials at base, on laterals much reduced on adaxial side, abaxially in a short, conspicuous band of irregularly but densely arranged stomata, adaxially dull dark green or yellow-green with whitish-green stomatal band, bearing a single resin cavity, eglandular. Pollen cones terminal, solitary, 2.5–5.0 mm, subglobose to ovoid, yellowish-green maturing light brown; microsporophylls decussate, 8–14, peltate, margins entire, bearing 4 abaxial yellow, microsporangia containing spherical pollen. Seed cones terminal on branchlets with monomorphic leaves of equal size, initially consisting of 2 decussate pairs of acute, 3–4 mm long, spreading bracts subtended by 4–5 similar but gradually smaller leaf pairs, the upper pair developing within one growing season to become thinly woody, together forming a cone 8–12 mm long. Bract-scale complexes 7–10 mm long, ± finely rugose, recurved in upper half above the abaxially exserting bract, subtended by the lower, smaller (3–4 mm long) less modified pair. Ovules 4, erect. alternating with each fertile bract. Seeds 2–4, 2–3 mm long, ovoid, flattened, with an acute apex, brown, with a whitish hilum and 2 opposite, thin, unequal, membranous wings, smaller 1 mm wide, larger, irregularly oval-oblong, 4–5 × 2.3 mm, yellowish brown. Cotyledons 2, juveniles leaves only on seedlings, ± acicular, on lower stem in whorls of 4 but soon decussate, bilaterally flattened, acuminate, the facials only slightly smaller, transitional leaves prevalent through much of life of young trees.