CYRTOSPERMA CUSPIDISPATHUM
PROTOLOGUE:
Cyrtosperma cuspidispathum Alderw., published in Bulletin du Jardin Botanique de Buitenzorg sér. 3, 1: 374 (1920), in "New or noteworthy Malayan Araceae".
Type: Gjellerup 63, Papua, Eta River⁴ (spelled "Eti River" in the protologue²), upper Tami, 2 April 1910, "shady clayey river side; alt. 85 m" (holotype B, not seen by Hay; isotype L).
Translated from protologue: Petiole about 75 cm long, dark olive- and purple-flamed, sparsely and shortly prickly; blade hastate or sagittate-hastate, about 50 cm long, the anterior lobe oblong, about 20 by 7 cm, abruptly and slenderly beaked at the tip rather than acuminate, the posterior lobes obliquely sublanceolate, about 30 by 10 cm, parted by a right-angled sinus, the posterior costae slightly decurved, bare in the sinus for 0.5–1 cm, unarmed beneath. Peduncle about 85 cm, sparsely prickly below and rather copiously so towards the top. Spathe about 35 cm long, dark violet, sparsely veined, the lower part long-oblong, about 18 by 4 cm, abruptly narrowed into a linear cusp, sharply subulate towards the tip and about as long as the lower part. Spadix stipitate, the stipe about 1 cm, cylindric, about 7.5 cm long and 6 mm thick, greenish white; tepals and stamens six; ovaries cylindric, flattened at the base, rounded and truncate at the apex, one-ovulate.² Alderwerelt added that the New Guinea plants Engler had determined as C. merkusii belong to three species, this one, C. subulispathum and C. hastatum.²
SYNONYMS:
HOMOTYPIC SYNONYMS: N/A
HETEROTYPIC SYNONYMS: N/A. Engler's New Guinea records of Cyrtosperma merkusii and C. edule (1879, 1911) and Krause & Alderwerelt's C. macrotum (1924, as to specimens cited) belong here in part.⁴
ACCEPTED INFRASPECIFICS: N/A
DISTRIBUTION:
New Guinea: New Guinea.¹
DISTRIBUTION NOTE: Indonesian Papua (Jayapura: Eta River) and Papua New Guinea in Sandaun (West Sepik), East Sepik, Madang, Western, Southern Highlands and Gulf Provinces.⁴ Herbarium records span 24 to about 760 m, median c. 300 m.⁵
SPECIES DESCRIPTION:
Moderately robust to gigantic, solitary or rarely suckering herb to c. 4 m tall; rhizome creeping, subterranean, up to 13 cm in diameter but very short because the older parts rot quickly. Leaves 2 to several; petiole brown, green, or mottled in combinations of these with white; armature sparse to dense, the spines, at least in the lower parts of the petioles and peduncles, small, squat, abruptly upturned and easily dislodged; petioles standing subparallel, not distinctly diverging from the base; blade hastate or sagittate, to 1.3 m long, in smaller plants often with the lobes much narrower than long, held with the posterior lobes down and the anterior lobe up, somewhat flaccid, unarmed.⁴
INFLORESCENCE:
Peduncle somewhat shorter than the petioles. Spathe 17 to c. 100 cm long, clasping in the lower quarter, ovate-lanceolate, in smaller plants erect, with increasing size the apical acuminate portion somewhat reflexed to greatly elongated, spirally twisted and dangling, purple-brown, usually with yellow veins outside and with pale pink to cream streaks toward the midline within; spadix to 18 cm long in flower, with a free, sometimes armed stipe 2–6 cm long. Flowers hexamerous; anthers not exceeding the tepals at male anthesis; stigmas more or less sessile, white turning brown; ovaries predominantly uniovulate, rarely biovulate. Fruit when ripe expelled from the spadix and held there by the stripped-away adaxial epidermis of the tepals. Seed slightly and irregularly ridged.⁴
ECOLOGY:
Lowland rainforest undergrowth and regrowth, predominantly on alluvial soils; one collection from lower montane forest on limestone at 500–600 m.⁴ In the Gogol Valley plants in logged regrowth reached the maximum size recorded for the species seven years after clearing, and seedlings establish in one-year-old regrowth.⁴
DISTRIBUTION MAPS:
Hay 1988 Fig. 8.
ETYMOLOGY:
From the Latin cuspis, a point, and spatha: the spathe drawn out into a long, tapering cusp.
NOTES:
1. One of the giants of the genus, with C. giganteum and C. timikense; Hay & Imran (2020) compare their C. timikense with this species, which it most resembles.⁶
2. Flowering is protogynous. The stigmas become receptive shortly after the spathe unrolls, in a rapid basipetal sequence over about two days, and remain receptive for about three weeks, each bearing a drop of nectar, unless pollination has occurred. Pollen is released only after the stigmas have ceased; the anthers open by apical pore-like slits and extrude the pollen in coherent rope-like masses, all the anthers of a flower together and in a slow basipetal sequence lasting several weeks along the spadix, the larger the inflorescence the longer the anthesis.⁴
3. Once the nectariferous stigmas stop there is no reward but pollen. Weevils, Trochorhopalus strangulatus, a species ranging from the Indian to the Pacific Ocean, feed on the tissue inside the base of the spathe. The inflorescence emits a faint musty, fruity odor day and night before, during and shortly after anthesis.⁴
4. As the inflorescence becomes an infructescence the geniculus at the top of the peduncle turns the spadix from pointing vertically up to pointing vertically down.⁴
5. Ripe fruits are pushed out of the spadix, presumably by the pressure of their own growth, and dangle from it by the inner epidermis of the tepals, which is stripped away as they emerge; they recall arillate seeds hanging by their funicles. In most Cyrtosperma the fruits stay attached until removed or until the spadix disintegrates; the mechanism is otherwise familiar in Anthurium.⁴
6. The New Guinea specimens Engler cited under C. merkusii and C. edule were not located by Hay and may have been destroyed in Berlin, but from their localities they are almost certainly this species; Engler's Pflanzenreich fig. 6, captioned C. edule, is clearly this plant.⁴
7. In cultivation at Lae the rhizomes suckered into large clumps, which Hay did not see in the wild.⁴ Indonesian growers now cultivate it, and it appears among iNaturalist records as garden plants.³
8. Plants raised from seed that the late Lynn Hannon and Julius Boos shared in 2004, from her plant of Cyrtosperma cuspidispathum, may be hybrids. On May 3rd, 2008, Boos wrote that photographs sent to him by at least two recipients of the seed showed blooms with pinkish striping and spathes shorter than the species', features he associated with the few hybrid Cyrtosperma, produced in Australia, that Hannon also grew in her greenhouse, and he suspected that insects had carried pollen from one of those hybrids onto her plant; this was his judgment from photographs, not a determination of the plants themselves.⁹
9. In cultivation the species can bloom well before it reaches full size. On October 11th, 2004, Boos wrote that his own plant of Cyrtosperma cuspidispathum bloomed at about 1.5 m (5 feet) tall and kept growing, and that a friend's seedling of the species had reportedly bloomed when only about 15 cm (6 inches) tall.¹⁰ On June 28th, 2007, Michael Mattlage showed a greenhouse plant in bloom, a juvenile about three years from seed that he named as Cyrtosperma cuspidispathum.¹¹
STORY:
STORY TITLE: The fruit that hangs itself
When the berries of Cyrtosperma cuspidispathum ripen they are pushed out of the spadix and left dangling from it, held on threads of the stripped inner epidermis of the tepals. The only other aroids known to do this are Anthurium.
The flowering is stranger still. Stigmas turn receptive in a wave running down the spadix over about two days, each carrying a drop of nectar, and stay receptive for roughly three weeks unless something pollinates them. Only then does pollen appear, released over several more weeks from pore-like slits in slow, coherent, rope-like masses. The inflorescence smells faintly musty and fruity, day and night. Weevils live inside the base of the spathe and eat the tissue there.
And as the fruit ripens, the geniculus at the top of the peduncle turns the whole spadix over until it points straight at the ground.
REFERENCES:
1. Plants of the World Online, Royal Botanic Gardens, Kew — Cyrtosperma cuspidispathum.
2. Alderwerelt van Rosenburgh, C.R.W.K. van. 1920. New or noteworthy Malayan Araceae. Bulletin du Jardin Botanique de Buitenzorg sér. 3, 1: 374 — protologue.
3. iNaturalist: Cyrtosperma cuspidispathum
4. Hay, A. 1988. Cyrtosperma (Araceae) and its Old World allies. Blumea 33: 427–469
5. GBIF occurrence download for Cyrtosperma, 2026-09-05 (59 records)
6. 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.
7. Krause, K. & Alderwerelt van Rosenburgh, C.R.W.K. van. 1924. Nova Guinea 14: 215.
8. Engler, A. 1911. Araceae-Lasioideae. Das Pflanzenreich IV.23C: 17–20, fig. 6
9. Aroid-L mailing list, Julius Boos, May 3rd, 2008
10. Aroid-L mailing list, Julius Boos, October 11th, 2004
11. Aroid-L mailing list, Michael Mattlage, June 28th, 2007
Additional photos from iNaturalist by Russell Cumming, johnpaulhouston, Mehd Halaouate, Yanuar Ishaq Dc, Bayan Izzani, Nusantara Wilderness, Refer Iqbal and Cheongweei Gan