Lophopetalum tanahgambut

Ecology and phenology: — In intact peat swamp forest with soil conditions that are always wet to flooded. In its type location, this new species is relatively rare and its seedlings are found very far from mature trees, this is probably due to the mechanism of winged seeds dispersing the seeds far from the parent trees. Lophopetalum tanahgambut was observed flowering during February – April, and fruiting in April – June.

Sumber: Lophopetalum tanahgambut, a new endemic giant tree species from peat swamp forest of Sumatera, Indonesia, with the first pseudoverticillate leaf arrangement in genus Lophopetalum (Celastraceae)

Uses: — The wood is used locally for carpentry.

Sumber: Lophopetalum tanahgambut, a new endemic giant tree species from peat swamp forest of Sumatera, Indonesia, with the first pseudoverticillate leaf arrangement in genus Lophopetalum (Celastraceae)

Provisional conservation status assessment: — Critically Endangered: CR A 2 cd C 2 a (i) (IUCN 2019). Lophopetalum tanahgambut grows in relatively undisturbed lowland peat swamp forest, which is protected by voluntary commitment of the concession as a conservation and retirement area. More extensive collecting in the wider area may reveal otherwise, but for now we must assume a small population size and a restricted distribution in Sumatera. While overall, undisturbed peat swamp forests have declined and under threat across Southeast Asia, and most remaining peatlands are converted to agriculture or degraded due to drainage (Miettinen et al. 2017; Page et al. 2022).

Sumber: Lophopetalum tanahgambut, a new endemic giant tree species from peat swamp forest of Sumatera, Indonesia, with the first pseudoverticillate leaf arrangement in genus Lophopetalum (Celastraceae)

Large top canopy tree, up to 40 m tall and 105 cm dbh; buttresses narrow, to 1.8 m tall; stilt-roots absent or sometimes present on old trees; knee roots system wide, to 15 m around the tree, raised to 1.5 m high from the ground surface, smooth, milky white to greyish. Bark smooth, cracked longitudinally to flaky, light to dull grey, or milky white; inner bark pinkish orange to pale reddish brown; sapwood cream. Lateral branches pseudoverticillate from seedling to pole and sometimes to early mature tree stage; young twigs with 3 – 4 obtuse angular, glabrous, plain green to becoming light and dull brown by aging, nodes thickened. Leaves in pseudoverticils of 3 – 4, arranged at a single plane around the axils or somewhat unequally within a node; blade coriaceous, often obovate or elliptic, sometimes lanceolate to oblanceolate, 6.1 – 12.4 × 3.0 – 6.6 cm; base cuneate to slightly winged onto petiole; margin entire, recurved; apex retuse to emarginate or sometimes shortly acuminate; adaxial surface flat, slightly bullate to furrowed above, dark green, glabrous, often with scattered black dots on young leaves; abaxial surface with visible scattered reddish-brown gland dots, pale green to whitish when fresh, glabrous; midrib prominent on both sides; secondary veins slender, 8 – 12 pairs, arching for whole length, anastomosing to margin, slightly raised on both sides or sometimes sunken adaxially; tertiary venation reticulate, visible on both sides when fresh, flat to sunken adaxially or sometimes slightly raised; young leaves pale reddish-brown, shiny. Petiole 0.7 – 1.2 cm long, stout, ascending, slightly twisted, with a pair of ridges to conspicuously winged, shallowly channelled or flat to slightly convex adaxially, rounded abaxially, yellowish green when fresh, glabrous, sometimes pruinose when old. Panicles borne from terminal leaf axils, solitary in an axil, up to 11.5 cm long, branching to 2 - orders, each branchlets bearing solitary flower, glabrous throughout, dull white to yellowish cream or greenish white when fresh; peduncle 2.5 – 4.5 cm long; rachis and branches 4 - angular; branches arranged (sub) opposite, spiral or in pseudoverticillate; bracts persistent, wide triangular, 1.0 - 1.4 × 1.9 – 3.5 mm, apex acuminate, drying early; bracteoles consistently in a pair at the end of branchlet, ca. 1.0 × 1.4 cm, thickened and fleshy. Flower buds short conical to ovoid, as high as wide or wider than high, 2.2 – 3.8 × 2.2 – 4.1 mm. Flowers 8.5 – 9.2 mm diameter at anthesis; pedicel 4.0 – 6.4 mm long; calyx lobes widely ovate, much wider than long, ca. 1.1 × 2.2 mm, apex rounded or sometimes obtuse, margins erose, papillate outer side, milky white; petals 5, imbricate, triangular or sometimes elliptic-oblong, 3.8 – 4.1 × 2.8 – 3.0 mm, white, glabrous on both sides, apex rounded to obtuse, margins erose, translucent, appendage conspicuous on the inner side, slightly sunken and papillate on outer one; disk convex, 4 – 5 mm diameter, 5 - angular with rounded corners, slightly thickened at lobes edges, dull white to pale yellow when fresh; stamens 5, inserted near disk lobes edge; filament whip-like, 1.3 – 1.8 mm long, thickened at base and tapering at the end; anther medifixed, ovoid, ca. 1.1 × 0.8 mm, base cordate, apex acute to slightly attenuate; pistil emerging 2.0 – 2.2 mm above the disk; ovary partly immersed in the disk, distinctly pyramidal at half base then narrowed into a cylindrical style; ovule 3 – 5 in each cell. Fruit generally ellipsoid, rarely oblong, 3 - lobed, 5.5 – 10.5 cm long, 2.4 – 3.2 cm at the widest point, distinctly three-lobed in cross section, greenish yellow when mature, glabrous and flat surface when fresh, apex shortly acuminate, split open while still hanging to release the winged seeds; dried fruit tuberculate on outer surface, rusty brown. Seed attached in the middle, surrounded by wing entirely, flattened, 4.4 – 5.6 × 1.2 – 1.5 cm (wing included), seed proper cream, wing milky white, drying early before fruit splits.

Sumber: Lophopetalum tanahgambut, a new endemic giant tree species from peat swamp forest of Sumatera, Indonesia, with the first pseudoverticillate leaf arrangement in genus Lophopetalum (Celastraceae)

Distribution: — The species is only known from peat swamp forests habitats in the type locality (Fig. 3). The type locality is a High Conservation Value Forest in a pulpwood concession on the border of Berbak Sembilang National Park. The peat swamp forest spans the border between Jambi and South Sumatra Provinces. A wider distribution in similar peat swamp forest habitats along the east coast of Sumatera is possible. However, large scale conversion and degradation of peatlands in the past has fragmented and reduced the extent of intact peat swamp forest. As this species has only been found in intact peat swamp forests and not degraded or restoration sites in areas adjacent areas to the type swamp forest its actual extent under current peatland conditions is most likely limited (Wijedasa et al., 2020).

Sumber: Lophopetalum tanahgambut, a new endemic giant tree species from peat swamp forest of Sumatera, Indonesia, with the first pseudoverticillate leaf arrangement in genus Lophopetalum (Celastraceae)