Metroxylon sagu Rottb.

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, multi-stemmed, palm to ca. 20 m, bearing 11–16 leaves per crown

Morphology Stem

Stem 35–45 cm diam., internodes 8–14 cm, stem surface with short, spine-like adventitious roots

Morphology Leaves

Leaf to 8 m long including petiole; sheath at least 1 m long, often with white indumentum, unarmed or armed with spines up to 5 cm long, spines arranged in collars, often detaching and leaving persistent ridges of united spine bases; petiole to 2.7 m long, armed as sheath; leaflets 60–77 each side of rachis, usually armed with marginal spines, linear elliptic; mid- leaf leaflets 122–146 × 5–11 cm wide; apical leaflets ca. 45–47 × 1–1.5 cm wide, linear, not united

Morphology Reproductive morphology Inflorescences

Inflorescence up to 4 m long including peduncle to 1.5 m, widely spreading and arching upwards, up to 27 inflorescences produced simultaneously along apical section of stem that extends up to 5 m above leaves; primary branches up to 25 per inflorescence, to 80 cm long, with up to 16 rachillae each; rachillae 8–14 × 1.1–1.6 cm long

Morphology Reproductive morphology Flowers

Flower 4–5 × ca. 2.5 mm in bud, green; stamens 6, orange-red

Morphology Reproductive morphology Fruits

Fruit 30–40 × 31–46 mm diam. Seed 20–25 × 23–33 mm.

Distribution

Thought to be native to Maluku and New Guinea, where it is very widespread, growing in wild and semi-cultivated or managed stands. Available specimen records (as presented on the map here) do not adequately represent the extent of the species Widely cultivated elsewhere in South-East Asia, sometimes on a plantation scale.

Ecology

Swamp forest, including disturbed habitats, where it often occurs in vast stands, typically at very low elevations. It is reported to grow at up to 1,200 m (Ehara et al. 2018).

Vernacular

Sagu, Rumbia (Bahasa Indonesia), Saksak (Papua New Guinea Tok Pisin); Metroxylon sagu has numerous local names in New Guinea, some of which are summarised by Bintoro et al. (2018). For brevity, we list only a fraction here: Aburi (Foi), Aiyo wo (Kubo), Ambe (Kosarek Yale), Ampehi (Ambai), Anane anapi (Yawa), Anannga (Wandamen), Bia (Patpatar), Bom (Nobonob), Hiywa (Angal Heneng), Kaniw (Kwerba), Keker (Marind), Naep (Amanab), Nggi (Morori), Õkõma (Yamben), Om (Telefol), U’tieh (Irarutu), Wi (Kamoro), Yof (Gebe).

Conservation

Least Concern (IUCN 2018).

Note

Nevertheless, Rauwerdink formally recognised four forms with M. sagu corresponding to different degrees of armature, which he regarded as “only slightly different genotypes of a single species”. Subsequently, however, Kjaer et al. (2004) demonstrated that there was no genetic correlation with armature in M. sagu across Papua New Guinea. Based on this, we regard M. sagu as a single variable species and treat all infraspecific taxa as synonyms. The true sago palm, M. sagu, is fundamentally important to livelihoods in New Guinea (Ehara et al. 2018). The species is morphologically variable (e.g. in armature) and this, in conjunction with its economic importance, has resulted in a proliferation of names and infraspecific taxa (the synonymy provided above is only a summary of the most important names). Rauwerdink (1985) reduced all names into a single variable species, including M. rumphii, then distinguished as the spiny sago palm as opposed to the spineless sago palm, as M. sagu was interpreted at the time. He justified this mainly on the basis of well-established observations that the offspring of a spiny sago palm can be either spiny or spineless.

Use

Exceptionally important as a source of edible starch obtained from the stem, making it the main carbohydrate staple for many indigenous groups in New Guinea. The leaves are used for thatch, house walls, other construction materials, brooms, baskets, and skirts for dances. Young shoots are consumed as vegetables. The stems are used to raise edible sago grubs. Young trunks, pith and pith refuse are fed to animals. The bark of the trunk is used as timber. Sago flour is burnt and eaten to reduce stomach pain. The starch paste is also applied on skin burns. The inflorescence bracts are folded and sown to form a watertight bucket. Fruits are eaten by the northern cassowary (Pangau-Adam & Mühlenberg 2014). The roots are used to treat measles.