CYRTOSPERMA GIGANTEUM
PROTOLOGUE:
Cyrtosperma giganteum Engl., published in Nova Guinea 8(1): 249 (1910), in Engler & Krause's Araceae of the Lorentz expedition.
Type: Versteeg 1818, Papua, Noord (Lorentz) River, flowering October 1907 (lectotype BO, chosen by Hay 1988); Versteeg 1141, May 1907 (BO, L), is the other original gathering, and Engler also cited von Römer 193 of 1909, which has not been located.⁴,⁶
Translated from protologue: Leaf with petiole to 2.5 m long, the adult blade coriaceous, ovate-sagittate, the anterior lobe to about 75 cm long and 70 cm wide at the base, obtuse or apiculate at the apex, the posterior lobes to 1 m or more long and 50 cm wide, bent back, subacute, separated by a deep acute sinus, with about eight distant primary lateral nerves joined into a marginal collective vein, the posterior costae bare in the sinus for about 10 cm. Peduncle to 4.5 cm in diameter, smooth. Spathe ovate-lanceolate with a long acumen, reddish brown, convolute below, about 8 cm across and about 35 cm or more long; spadix dark rose, stipitate for 2 cm, 21 cm long and about 4 cm thick. Stamens 4–5, 3 mm long, on filaments up to 1 mm. Pistil 4 mm long, the ovary with several ovules. Perianth of 4–5 tepals 3.5 mm long. Fruiting spadix to 36 cm long and 9 cm thick. Berries ellipsoid, green, 1.5 cm long and 6 mm thick. Seeds several.²
SYNONYMS:
HOMOTYPIC SYNONYMS: N/A
HETEROTYPIC SYNONYMS: N/A
ACCEPTED INFRASPECIFICS: N/A
DISTRIBUTION:
New Guinea: New Guinea.¹
DISTRIBUTION NOTE: Indonesia, Papua Province, in the Mimika and Asmat Regencies of the southern lowlands.⁶ First collected in 1907 by G.M. Versteeg and again in 1909 by L.S.A.M. von Römer on the Noord River, renamed the Lorentz in 1910 and now the Unir of the Asmat people; Hay knew it only from those gatherings.⁴ There was then no scientific record for over ninety years, until R.J. Johns collected it in 1999 and 2000 on the Freeport concession in the Mimika Regency (Johns 9831 and 10638, K), an encounter published only as the habit photograph that illustrates the genus on POWO, and Imran photographed it near Timika in 2020.⁶ GBIF also lists specimens from Western Province, Papua New Guinea, which Hay & Imran do not cite.⁵
SPECIES DESCRIPTION:
Massive pachycaul rhizomatous evergreen herb 3–4 m tall; rhizome dense, more or less without internodes, c. 40 cm thick with the leaf-base remains. Leaves several together; petioles stout, somewhat spreading, plain green, 1.3–2 m long and c. 12 cm thick toward the base, with crowded to scattered small prickles at the base and increasingly scattered prickles above, sheathing in the lower sixth or so, somewhat channelled above, filled with air cavities to 1 cm across, geniculate for several centimeters at the apex; blade ovate-sagittate, held more or less vertical with the posterior lobes down, somewhat irregularly wrinkled and bullate between the primary veins, to c. 2.25 m long by c. 1.2 m wide at the petiole insertion and somewhat wider behind it; anterior and posterior lobes about equal or the posterior somewhat longer; the costae massive, to 3 cm thick at the base, impressed above and very prominent beneath, the anterior costa with c. 10 robust primary lateral veins, the posterior costae diverging at 40–60° and naked in the sinus for c. 10 cm; posterior lobes with their outer sides overlapping each other; finer venation reticulate.⁶ Engler's description, from herbarium material, gave the petiole to 2.5 m, the coriaceous blade with the anterior lobe to about 75 by 70 cm and the posterior lobes to 1 m or more long, and Hay added that the blade and upper petiole are unarmed and the lower petiole armed with scattered straight spines.²,⁴
INFLORESCENCE:
Blooms solitary, but up to three or more in close succession, each separated by a foliage leaf; peduncle much shorter than the petioles, c. 50 cm long and 4.5 cm thick, unarmed or with a few scattered prickles, tinged brown, larger and plain green in fruit, inconspicuously geniculate near the apex. Spathe more or less canoe-shaped, erect, 35–50 cm long, convolute in the lower c. 8 cm, narrowed and acuminate in the upper third, greenish brown at the base and then burgundy-red to yellowish brown outside, cream to yellow with faintly purple-suffused streaks within. Spadix on a 2 cm stipe, stout, tapering-cylindric, 21–30 cm long and 4–5.5 cm thick below, blunt, dull brownish pink; florets bisexual, extremely numerous (over 2,000 to a spadix), rhomboid to hexagonal from above, c. 3 mm across; tepals 4–6, free, c. 3.5 mm long; stamens 4–6 with free filaments c. 1 mm long, the anthers partly exserted at male anthesis; pistil c. 4 mm, the stigma button-like and more or less sessile, the ovary unilocular with several ovules. Infructescence massive, deflected by the genicular zone near the top of the peduncle and accompanied by the marcescent spathe, the fruiting spadix 36–45 cm long and 9–11 cm thick; berries ellipsoid, c. 1.5 by 0.6 cm, their more or less pointed tips protruding from the tepals, dark green ripening yellow, with 1–5 seeds; seeds reniform, longitudinally crested, 5–6 mm long.⁶ Hay counted some 1,300 fruits on a preserved infructescence, by far the largest in the genus, and found the seeds crested like those of C. merkusii.⁴
ECOLOGY:
Open swampy areas with scattered sago palms (Metroxylon) and Campnosperma, and disturbed swamp forest with Campnosperma, Nauclea and Pandanus, at very low elevation, 10–15 m.⁵,⁶
DISTRIBUTION MAPS:
Hay 1988 Fig. 3.
ETYMOLOGY:
Latin giganteus, gigantic: the leaves and infructescence are the largest in the genus.
NOTES:
1. Its 4–6-merous flowers, pluriovulate ovary and multi-seeded berries are unique in Cyrtosperma and led Engler to ally it with the African Lasimorpha senegalensis; the marcescent spathe, the geniculate petiole and peduncle and the free filaments place it in Cyrtosperma proper, and the exserted anthers and crested seeds put it, tentatively, in the Merkusii group.⁴,⁶
2. Named by Engler in Engler & Krause's account of the Araceae of the Lorentz expedition, from Versteeg's collections; the type locality's river has carried three names, Noord, Lorentz and Unir.²,⁶
3. Hay & Imran (2020) gave the first illustrations of the living plant, photographed by Imran near Timika, with an updated description a hundred and ten years after the protologue. They set it beside C. cuspidispathum as one of the two most gigantic New Guinea aroids, and in a note added in proof announced a third, C. timikense, described later in the same issue.⁶,⁷
4. The ripe berries protrude from the tepals but are not expelled; the "anthuriocarp", in which the expelled fruits hang from the spadix by the stripped inner epidermis of the tepals, is known in the genus only in C. cuspidispathum and, from Imran's observations near Timika, in C. hambalii.⁶
5. Now in cultivation: iNaturalist records from 2025 and 2026 include garden plants.³
STORY:
STORY TITLE: A hundred and thirteen years between the collection and the photograph
In 1907 Versteeg collected a huge lasioid twice on the Lorentz River in what is now Papua, once in May and once in flower that October. Hay chose the October gathering as lectotype in 1988 and could add almost nothing to it, because nobody had been back. For most of a century the species existed as a pair of sheets in Bogor.
Then in 2020 Hay and Imran published photographs of a living plant: the first images of Cyrtosperma giganteum ever printed.
Its flowers are 4- to 6-merous with a pluriovulate ovary and multi-seeded berries, a combination found nowhere else in the genus. The berries push out through the tepals but stay on the spadix rather than hanging free. Its seed is now sold commercially, which means more people may grow it in the next decade than have ever seen it wild.
REFERENCES:
1. Plants of the World Online, Royal Botanic Gardens, Kew — Cyrtosperma giganteum.
2. Engler, A. 1910. Araceae. Nova Guinea 8(1): 249 — protologue.
3. iNaturalist: Cyrtosperma giganteum
4. Hay, A. 1988. Cyrtosperma (Araceae) and its Old World allies. Blumea 33: 427–469
5. GBIF occurrence download for Cyrtosperma, 2026-09-05 (17 records)
6. Hay, A. & Imran. 2020. Cyrtosperma giganteum Engl. (Araceae–Lasioideae) found again in Papua Province, Indonesia. Aroideana 43(3–4): 4–11.
7. Hay, A. & Imran. 2020. A third enormous New Guinea lasioid — Cyrtosperma timikense, a new species from southern Papua Province, Indonesia. Aroideana 43(3–4): 97–107.
8. Engler, A. 1911. Araceae-Lasioideae. Das Pflanzenreich IV.23C: 17
Additional photos from iNaturalist by flora and fauna of papua indonesia, avamliu and Nusantara Wilderness