Arecaceae
Borassus

Borassus heineanus Becc.

First published in Webbia 4: 354 (1914)
This species is accepted
The native range of this species is N. New Guinea. It is a tree and grows primarily in the wet tropical biome.

Descriptions

Baker, W.J., Barfod, A.S., Cámara-Leret, R., Dowe, J.L., Heatubun, C.D., Petoe, P., Turner, J.H., Zona, S. & Dransfield, J. (2024) Palms of New Guinea. Royal Botanic Gardens, Kew, Richmond. 726 pp.

Morphology General Habit
Robust, single-stemmed tree palm to 25 m
Morphology Stem
Stem ca. 40 cm diam. Leaf 20–28 in the crown; petiole and sheath 150–300 cm long; petiole 3.1–5.2 cm wide at midpoint, green with very sharp black margins, but no spines; costa 130–150 cm long, hastula conspicuous, to 1.2 cm, blade radius to 180 cm; segments 50–90, 3.9–7.1 cm wide, apices bifid, blade divided to 76–92 cm, transverse veinlets conspicuous
Morphology Reproductive morphology Inflorescences
Inflorescence male to 1.2 m long, branched to one order, female to 80 cm long, unbranched; male rachilla cylindrical, to 70 cm long, 2.7–4.3 cm diam., rachilla bracts forming pits containing 6–12 flowers; female rachilla 37–49 cm long with 7–22 flowers arranged spirally
Morphology Reproductive morphology Flowers
Female flower 2.5 × 2 cm Male flower 0.4–1 cm long, stamens 6
Morphology Reproductive morphology Fruits
Fruit large, 12–15 × 8–10 cm, ovoid with a slightly pointed apex, greenish black; pyrenes 1–3, 9.2–10.5 × 4.8 -7.0 × 4.0–4.5 cm; endocarp sometimes with flanges penetrating seed
Morphology Reproductive morphology Seeds
Seed with homogeneous endosperm; embryo apical.
Distribution
Restricted to central northern New Guinea.
Ecology
In lowland forest from sea level to 60 m.
Vernacular
Beiwof (Apau), Lipmemon (Kamangauwi dialect).
Conservation
Near Threatened. Borassus heineanus is threatened at several sites by mining and logging concessions.
Note
Borassus heineanus is instantly recognisable as the only massive tree palm with fan leaves that have cleft leaf bases and unarmed petioles with very sharp margins. The cleft leaf bases are also known in Corypha utan, but that palm has conspicuous teeth along the petiole margins. The fruit of B. heineanus is among the largest fruit of any palm in New Guinea, and yet it is known to be consumed by cassowaries, which disperse the sizeable seeds (Pangau-Adam & Mühlenberg 2014).
[PONG]

Bayton, R. (2007). A Revision of Borassus L. (Arecaceae). Kew Bulletin, 62(4), 561-585. Retrieved from http://www.jstor.org/stable/20443389

Type
Papua New Guinea, Sepik River, Heine s.n. (holotype FE!).
Morphology Stem
Stem to 25 m tall, stem diameter unknown
Morphology Leaves
Leaves 20 - 28 in the crown; petiole and sheath 150 - 300 cm long; petiole 3.1 - 5.2 cm wide at midpoint, green with very sharp black margins, but no spines; costa 130- 150 cm long; adaxial hastula conspicuous, to 1.2 cm, abaxial hastula absent; lamina radius to 180 cm maximum; leaflets 50 - 90, 3.9 - 7.1 cm wide, apices bifid and cuspidate, shortest leaflet 110 - 130 cm long, leaf divided to 76 - 92 cm; commissural veins 3 - 6 per cm, leaf anatomy dorsiventral.
Morphology Reproductive morphology Inflorescences
Pistillate inflorescences spicate; flower bearing portion 37 - 49 cm long with 7 - 22 flowers arranged spirally Staminate inflorescences branched to one order, upper subtending branches terminating in 1 rachilla; rachillae brown and catkin-like, ± 70 cm long, 2.7 - 4.3 cm diameter; rachilla bracts forming pits containing a cincinnus of 6 - 12 flowers.
Morphology Reproductive morphology Flowers
Staminate flowers exserted from pits individually, 0.4 - 1 cm long, bracteoles 1 x 1 cm; calyx 0.3 x 0.8 cm, shallowly to deeply divided into three sepals, petal lobes 0.2 x 0.1 cm; stamens 6 with very short filaments, 0.11 x 0.15 cm, anthers 0.18 x 0.06 cm; pistillode distinct, 0.2 - 0.5 x 0.02 cm Pistillate flowers 2.5 x 2 cm; bracteoles large, 1.5 cm diam., sepals 1.5 x 2 cm, petals 1.0 x 1.5 cm
Morphology Reproductive morphology Flowers Pollen
Pollen monosulcate, elliptical, 51 - 70 μm long, aperture 41 - 63 μm long, polar axis 37 - 57 μm long; tectum perforate, sparsely covered with supratectal gemmae
Morphology Reproductive morphology Fruits
Fruits large, 12 - 15 x 8 - 10 cm, ovoid with a slightly pointed apex, greenish black; pyrenes 1 - 3, 9.2 - 10.5 cm x 4.8 - 7.0 cm x 4.0 - 4.5 cm; endocarp sometimes with flanges that penetrate the seed.
Distribution
Endemic to New Guinea. Occurring in both Papua New Guinea and Indonesian Papua, but restricted to the northern side of the island.
Ecology
Tropical rain forest on alluvial sands (Barfod et al. 2001). The palm may also be cultivated (Kjær 2003).
Conservation
Data deficient. Borassus heineanus has been collected in only seven locations in New Guinea. Kjær (2003) reported a stand of approximately 300 x 300 metres in an area by the Sepik River in Papua New Guinea. Additional localities may exist, and further collections are needed.
Note
After Georg Heine, administrator with the German New Guinea Company, who collected the type specimen. Borassus heineanus is by far the most distinctive species in the genus and this led Beccari (1924) to speculate that it should be transferred into Borassodendron. Both B. heineanus and Borassodendron occur in humid rain forest, generally an atypical habitat for Borassus. Unlike all other Borassus species, the petiole is always unarmed, the leaves have a dorsiventral leaf anatomy and cuspidate leaflet apices, the staminate inflorescence branches to one order only and the staminate flowers have a large pistillode. However, the pollen is very similar to that found in the other Borassus species; it has a sulcate aperture that is almost the length of the grain and a perforate tectum with sparse supratectal gemmae. In contrast, the pollen of Borassodendron has a porate aperture and no gemmae (Ferguson et al. 1986). Preliminary results from the molecular study confirm the monophyly of Borassus in its current circumscription (including B. heineanus) and suggest that Borassodendron is sister to Borassus (Bayton 2005). The pyrenes of Borassus heineanus are rather unusual for the genus. In most Borassus species, pyrene length and breadth are similar or equal, but in B. heineanus, the pyrenes are much longer than wide. While living material of B. heineanus has never been collected outside New Guinea, two endocarps (Degener & Degener 24625, BH) found on a beach on the Pacific island of Canton (Phoenix Is., Kiribati) were identified as belonging to Borassus (Degener & Degener 1974) and are probably attributable to this species. The endocarps are rather long and narrow and have perpendicular internal flanges (see Gunn & Dennis 1976: 177). These characters set them apart from all other Borassus species. However, typical endocarps of B. heineanus have a small hole in the apex to allow the cotyledonary stalk to exit. The Canton endocarps have deep V-shaped clefts at the apex, usually filled with black fibres (fibres eroded in one pyrene). There is a great deal of natural variation in the endocarps of better-known Borassus species. Perhaps when more material is collected in New Guinea, the presence of internal flanges or apical V-shaped clefts in the endocarp will fit into the natural range of variation exhibited by B. heineanus.
Vernacular
Beiwof (Apau), Lipmemon (Kamangauwi dialect).
[KBu]

Extinction risk predictions for the world's flowering plants to support their conservation (2024). Bachman, S.P., Brown, M.J.M., Leão, T.C.C., Lughadha, E.N., Walker, B.E. https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.19592

Conservation
Predicted extinction risk: not threatened. Confidence: confident
[AERP]

Uses

Use
Leaves used for thatch. Edible young fruits, which are also eaten by the northern cassowary.
[PONG]

Use
Very little is known about the uses of B. heineanus, though Kjær (2003) reports that the leaves are used for thatch.
[KBu]

Sources

  • Angiosperm Extinction Risk Predictions v1

    • Angiosperm Threat Predictions
    • http://creativecommons.org/licenses/by/4.0

  • Herbarium Catalogue Specimens

    • 'The Herbarium Catalogue, Royal Botanic Gardens, Kew. Published on the Internet http://www.kew.org/herbcat [accessed on Day Month Year]'. Please enter the date on which you consulted the system.
    • Digital Image © Board of Trustees, RBG Kew http://creativecommons.org/licenses/by/3.0/

  • Kew Backbone Distributions

    • The International Plant Names Index and World Checklist of Vascular Plants 2026. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0

  • Kew Bulletin

    • Kew Bulletin
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Kew Names and Taxonomic Backbone

    • The International Plant Names Index and World Checklist of Vascular Plants 2026. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 International Plant Names Index and World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0

  • Kew Science Photographs

    • Copyright applied to individual images

  • Palms of New Guinea

    • http://creativecommons.org/licenses/by-nc-sa/3.0