CYRTOSPERMA BRASSII

PROTOLOGUE:

Cyrtosperma brassii A.Hay, published in Blumea 33: 439 (1988), with Fig. 5.

Type: L.J. Brass 28282, Papua New Guinea, Milne Bay Province, Rossel Island, Abaleti, 1 October 1956 (holotype L; isotypes A, LAE). Hay's diagnosis: differs from C. merkusii in the tetramerous flowers, the smooth seeds and the leaves that are rough to the touch when dried.²

SYNONYMS:

HOMOTYPIC SYNONYMS: N/A

HETEROTYPIC SYNONYMS: N/A

ACCEPTED INFRASPECIFICS: N/A

DISTRIBUTION:

New Guinea: New Guinea (Rossel Island).¹

DISTRIBUTION NOTE: Confined to Rossel Island at the eastern end of the Louisiade Archipelago; besides the type, Brass 28251, NGF 27090 and a plant grown at Lae.² Records from 1956–1982, at 50 m.⁴

SPECIES DESCRIPTION:

Robust herb to 2.5 m tall. Leaves 2 to several; petioles spreading out from the base, very prickly with small spines arranged in combs at least toward the base, mottled green and white; blade sagittate, to 120 cm long, held with the anterior lobe up and the posterior lobes down; costae of the anterior lobe pinnate, spreading; posterior lobes with the midribs naked in the sinus for c. 6 cm, to 30 cm wide at the widest point, with acuminate tips; both surfaces of the blade rough (asperous) in the dry state though not when fresh.²

INFLORESCENCE:

Peduncle similar to but usually somewhat shorter than the petioles. Spathe ovate-lanceolate, to 18 cm long, remaining somewhat constricted above the level of the spadix apex after opening, boat-shaped, blackish purple, with parallel major venation and reticulate secondary venation; spadix with a c. 5 mm free, unarmed stipe, to c. 7 cm long, creamy yellow. Flowers tetramerous; ovaries 1(–2)-ovulate; anthers exserted from the tepals at male anthesis. Fruit ovoid, orange-red. Seed smooth, very faintly longitudinally ridged.²

ECOLOGY:

Rainforest on Rossel Island, at low altitude.²,⁴

DISTRIBUTION MAPS:

Hay 1988 Fig. 3.

ETYMOLOGY:

For Leonard J. Brass (1900–1971), the Australian botanist of the Archbold Expeditions who collected the type on the Fifth Archbold Expedition in 1956.

NOTES:

1. One of two Louisiade endemics, with C. gressittiorum on Sudest; both are tetramerous members of the Merkusii group, the group otherwise hexamerous.² With C. bougainvillense they are the closest relatives of the giant swamp taro, which bears on the question of where that crop came into cultivation.²

2. Grown at the Lae Botanic Gardens in the 1980s, from which Hay drew the figure.²

3. ⚠ No photograph of a living plant was found.

STORY:

STORY TITLE: Four-parted flowers at the eastern edge

One of two species confined to the Louisiade Archipelago, the other being Cyrtosperma gressittiorum on Sudest. Both are tetramerous, with flowers built on four parts, in a group otherwise built on six. Hay kept them in the Merkusii group regardless, on the stamens exserted at male anthesis.

That is the pattern at the eastern limit of the genus: the flowers get simpler as the islands get smaller and further out.

It was grown at Lae Botanic Gardens in the 1980s. Almost nothing has been added since.

REFERENCES:

1. Plants of the World Online, Royal Botanic Gardens, Kew — Cyrtosperma brassii.

2. Hay, A. 1988. Cyrtosperma (Araceae) and its Old World allies. Blumea 33: 427–469 — protologue, p. 439.

3. iNaturalist: Cyrtosperma brassii

4. GBIF occurrence download for Cyrtosperma, 2026-09-05 (6 records)

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