CYRTOSPERMA PRASINISPATHUM
PROTOLOGUE:
Cyrtosperma prasinispathum A.S.D.Irsyam & M.R.Hariri, published in Webbia 79(2): 292 (3 September 2024), "Cyrtosperma prasinispathum: a new fascinating Aroid species from Papua, Indonesia".
Type: MRH 777, prepared 14 March 2024 from a living plant at the Bogor Botanic Gardens, Indonesia, Southwest Papua Province, Sorong Regency (holotype FIPIA, isotype BO). The Bogor plants grew from seed, DW1091, collected by Prof. Dr. Widyatmoko at Taman Wisata Alam Sorong at 27 m on 11 June–9 July 2007 and long labeled Cyrtosperma hambalii.²
Diagnosis: geographically associated with C. macrotum but differing in the unarmed abaxial leaf surface, the oblanceolate posterior lobes, the elliptic anterior lobe, the deflected spathe with an entire margin, the leek-green spathe, the yellowish-green to yellow spadix and the consistently tetramerous flowers.²
SYNONYMS:
HOMOTYPIC SYNONYMS: N/A
HETEROTYPIC SYNONYMS: N/A
ACCEPTED INFRASPECIFICS: N/A
DISTRIBUTION:
New Guinea: New Guinea (Southwest Papua Province, Sorong).¹,²
DISTRIBUTION NOTE: Known only from the 2007 Sorong collection and its descendants in cultivation at Bogor.²
SPECIES DESCRIPTION:
Small herb 21–30 cm tall. Leaves about 5–9 per crown, clustered; sheath 2–4 cm long, brown; petiole slender, 5–25 cm long, brown with black patches, armed with straight, downward- and mostly upward-pointing spines 1–4 mm long, yellowish brown; blade sagittate-hastate, the anterior lobe elliptic, shorter than the posterior lobes, 3.5–12 by 2–6.2 cm, pointing downward, flat in juvenile leaves; posterior lobes oblanceolate, 4.2–17 by 2–5.5 cm, pointing downward, the sinus 60–80 degrees; upper surface dark green, lower surface glaucous.²
INFLORESCENCE:
Peduncle 50–73 cm long, brown with black patches, armed with minute straight, downward- and mostly upward-pointing spines 1–2 mm long. Spathe broadly open, lanceolate, deflected, 10.9–11.5 by 2.5–2.9 cm, leek-green. Spadix 35–45 by 6–7 mm, yellowish green turning yellow when mature; stipe 3–6 mm long, leek-green. Flowers bisexual, perigoniate; tepals 4, free, green turning yellow; stamens 4, free, the filaments flat and broad, the anthers c. 0.5 mm long, white, not exserted from the tepals at anthesis; pollen white; ovary one-locular, brown; stigma discoid, sessile, brown.²
ECOLOGY:
Lowland forest of the Sorong nature reserve (Taman Wisata Alam Sorong) at 27 m; nothing more is recorded.²
DISTRIBUTION MAPS:
None published.
ETYMOLOGY:
From the Latin prasinus, leek-green, and spathum, for the glossy leek-green spathe.²
NOTES:
1. The fourth member of the Macrotum group, with C. beccarianum, C. macrotum and C. hayii; the group has a spathe not convolute in its lower part and tetra-, penta- or hexamerous flowers.²
2. Described entirely from living cultivated plants; the authors propose Data Deficient for its conservation status and note that the striking spathe makes it "an important candidate for horticultural plants".²
3. The authors' Figure 1 shows the habit, the three kinds of spine tip on the petiole, the spathe from three angles, the spadix and immature flowers, and compares the leaf with those of C. macrotum and C. hambalii.²
4. With C. hayii it brings the genus to 15 species, 14 of them east of Wallace's Line.²
STORY:
STORY TITLE: Number fifteen, in leek green
Described in 2024 by Hariri, Irsyam and Ariati from Indonesian New Guinea: the fifteenth accepted species of Cyrtosperma and, for now, the newest. It brought the Macrotum group to four.
Its authors call the striking spathe an important candidate for horticultural plants, which is the kind of line that tends to precede a plant appearing in trade.
Unusually, it was described entirely from living cultivated plants, and the authors propose Data Deficient for its conservation status.²
REFERENCES:
1. Plants of the World Online, Royal Botanic Gardens, Kew — Cyrtosperma prasinispathum.
3. Hay, A. 1988. Cyrtosperma (Araceae) and its Old World allies. Blumea 33: 427–469
Figure 1 panels A-H are from the protologue, Hariri et al. 2024, Webbia 79(2): 291–294, open access under CC BY