Cycas riuminiana

Cycas riuminiana is a cycad of the mountain forests of Luzon, in the Philippines, known in particular from Mount Arayat and the Sierra Madre and found as far north as the Batanes Islands. This species of the genus Cycas, the earliest described of the Philippine cycads (1863), is also known under the names Cycas chamberlainii, long used for the plants of Mount Arayat, and Cycas circinalis subsp. riuminiana. In the Philippines it is called pitogo, the Tagalog name for its seed. The IUCN lists it as Endangered.

Key facts about Cycas riuminiana

  • Accepted name: Cycas riuminiana Porte ex Regel (1863), accepted by The World List of Cycads (version 2026.08.15) and by GBIF; POWO could not be consulted
  • Former names and synonyms: Cycas chamberlainii W.H.Br. & Kienholz (1925); Cycas circinalis subsp. riuminiana (Porte ex Regel) J.Schust. (1932); Cycas truncata de Laub. (2007, illegitimate name); formerly often treated as Cycas circinalis or Cycas rumphii
  • Family: Cycadaceae, order Cycadales
  • Common names: no English name attested; pitogo, bayit, oliva, tamok (Tagalog), sawang (Ilocano)
  • Natural range: Philippines, Luzon and nearby islands (Bataan, Batanes, Batangas, Cagayan, Cavite, Isabela, Laguna, Pampanga)
  • IUCN status: Endangered (EN, criteria A4acd), assessment by Agoo, Madulid, Linis and Sambale (2010), reassessed by J.D. Bösenberg in Red List version 2023-1; EN according to GBIF
  • CITES and other protection: CITES Appendix II (seeds exempt under annotation #4); Annex B in the European Union
  • Documented hardiness: no data (see Cold hardiness)
  • Light and soil: in the wild, closed evergreen forest on ridges and steep slopes; no cultivation data
  • Habit and adult size: slender trunk up to 8 m tall, 5 to 10 cm across at its narrowest; leaves 1 to 1.9 m long
  • In the UK, US and Australia: Montgomery Botanical Center and Fairchild Tropical Botanic Garden (Florida), Lotusland and the Huntington (California), Honolulu; Royal Botanic Garden Sydney and Cairns; no British record
  • Toxicity: no data specific to the species; treat it as poisonous, like all Cycas (see Toxicity and precautions)

How to recognise Cycas riuminiana

In the Philippines, Cycas riuminiana stands out by its narrow leaflets with a midrib strongly raised on the upper surface, its long, sharp cataphylls (the scale leaves that protect the growing point) and its megasporophylls carrying up to 30 lateral spines 2 to 13 mm long and a slender apical spine up to 32 mm long (Lindström et al. 2008). Its leaves are flat in section and its seeds have a thin spongy layer. The description below is that of Lindström, Hill and Stanberg (2008).

  • Trunk: tree-like, up to 8 m tall and slender, 5 to 10 cm in diameter at its narrowest point.
  • Leaves: bright green, highly glossy or semi-glossy, 1 to 1.9 m long, flat in section (opposite leaflets at 180°), with 120 to 240 leaflets and a down that is shed as the leaf expands; petiole 25 to 55 cm long, hairless and more or less spiny; the lower leaflets do not shrink gradually into spines.
  • Median leaflets: 21 to 31 cm long and 7.5 to 13 mm wide, with slightly recurved margins and a bristle-pointed tip, 9 to 18 mm apart.
  • Cataphylls: linear, pungent and downy.
  • Male cones: ovoid to spindle-shaped, orange or brown, about 20 cm long and 6 cm in diameter; each microsporophyll ends in a prominent, sharply upturned spine about 11 mm long.
  • Megasporophylls (the fertile leaves of female plants): 15 to 24 cm long, brown-felted, bearing 4 to 10 ovules; the blade is lanceolate to elliptical, 43 to 65 mm long and 15 to 30 mm wide, shallowly comb-toothed.
  • Seeds: ovoid, 31 to 41 mm long and 24 to 26 mm wide; the yellow fleshy coat, 3 mm thick, has no fibrous layer, and a thin spongy layer surrounds the kernel.

Hybrids

No hybrid is documented for this species.

Possible confusion

Cycas zambalensis, from the ultramafic soils of Zambales province, is very similar; it differs in narrower, stiffer leaflets, keeled leaves and a downy petiole (Lindström et al. 2008). Cycas lacrimans, from Mindanao, has drooping leaves and seeds without a spongy layer. Cycas nitida, a coastal species, has seeds with a thick spongy layer and a much longer microsporophyll spine (13 to 23 mm). Cycas edentata, a cycad of the seashore, has almost toothless megasporophylls.

In cultivation, seeds distributed in the 1990s as “Philippines small seed”, said to come from Mindoro, appear to belong to this species; the mature plants raised from them are slightly more robust and have larger seeds than those of Luzon, but seem to fall within the variation of the species (Lindström et al. 2008). Their Mindoro origin has not been confirmed.

Taxonomy

Cycas riuminiana is a name accepted by The World List of Cycads and by GBIF; POWO could not be consulted. Eduard Regel, then scientific director of the Imperial Botanic Garden in St Petersburg, described it in 1863 in the journal Gartenflora (12: 16–17) without citing a type, probably from living plants in cultivation there. The plants had been imported from Manila by Porte and sold by the Moscow Horticultural Society through the Belgian nursery firm Verschaffelt; Lemaire published a description with a colour plate in 1864 in L’Illustration horticole. The typification is unsettled: de Laubenfels and Adema (1998) designated as lectotype a cultivated specimen at Kew, which Lindström et al. (2008) prefer to treat as a neotype, since nothing shows that it is original material, while The World List of Cycads gives a holotype at the herbarium of the Komarov Botanical Institute in St Petersburg (LE).

The name was then ignored for more than a century. Merrill (1923) placed it in the synonymy of Cycas rumphii. In 1925 Brown and Kienholz described Cycas chamberlainii from the plants of Mount Arayat, without reference to Cycas riuminiana. Schuster (1932) made it a subspecies of Cycas circinalis; Zamora and Co (1986) and Amoroso (1986) treated most plants as Cycas circinalis and kept Cycas chamberlainii for Mount Arayat alone. De Laubenfels and Adema (1998) united Cycas chamberlainii with Cycas riuminiana, but in a broad and unclear circumscription that also took in plants from Sulawesi now called Cycas falcata, which explains why their account gives Sulawesi and the Moluccas in its range. Lindström, Hill and Stanberg (2008) confirmed the synonymy with Cycas chamberlainii, restricted the species to the Philippines and placed it in section Cycas, subsection Cycas.

In 2007 de Laubenfels described Cycas truncata from a collection made by Merrill on Mount Mariveles. Hill and Stanberg (2009) showed that this name is illegitimate, because its author had included in its synonymy the older name Cycas inermis Lour., and that the specimens behind it fall within the variation of Cycas riuminiana. The World List of Cycads also lists Cycas circinalis var. curranii J.Schust. among the synonyms of Cycas riuminiana, whereas Lindström et al. (2008) refer that name to Cycas curranii. For the reader, a plant labelled Cycas chamberlainii, Cycas truncata or, for a Luzon provenance, Cycas circinalis very probably belongs to this species.

Etymology and history

The epithet honours a Mr Riumin, nineteenth-century Russian horticulturist and president of the Moscow Horticultural Society, which marketed the first plants (Lindström et al. 2008; Haynes 2022). His first name is not given in the sources consulted.

The story of the species therefore begins in cultivation, in Europe, before it was studied in the wild: it was the first Cycas reported from the Philippines (Lindström et al. 2008). Kew held a cultivated specimen as early as 1897. A Philippine collection by Loher from Arayat dates from June 1896.

Common names

No English common name is attested, and the British nursery Trebrown knows of none. Lindström et al. (2008), after Merrill (1923), Zamora and Co (1986), Amoroso (1986) and Bonta and Osborne (2007), record several vernacular names: in Ilocano, sawang (also spelt sauang); in Tagalog, bayit (bait, vait), oliva for the plant (oliba, uliba, uliva), pitógo for the seed (bitogo, patubo, pitugo, potago) and tamok. The Makiling Botanic Gardens, in the Philippines, use the name pitogo for the whole plant. These names may also be applied to other Philippine cycads.

In the wild

Cycas riuminiana is an inland species of wooded ridges and mountains, growing in closed mixed evergreen forest, usually on steep slopes. It is abundant in northern Luzon and extends south at least to Batangas province; collections also come from Batan Island, in the Batanes group (Lindström et al. 2008). The World List of Cycads cites the provinces of Bataan, Batanes, Batangas, Cagayan, Cavite, Isabela, Laguna and Pampanga; the records for Cagayan, Cavite and Laguna rest on Amoroso (1986), without a voucher specimen. Its presence on Mindoro is unconfirmed.

The Makiling Botanic Gardens report that the species is still abundant on Mount Arayat and on Mount Dipalayag, in the Sierra Madre. Pollination and phenology are not documented in the sources consulted.

Conservation status and regulation

The IUCN lists Cycas riuminiana as Endangered (EN) under criteria A4acd, which reflect a population decline, past and future, inferred from observation, loss of habitat and exploitation, in the assessment by Agoo, Madulid, Linis and Sambale (2010) cited by The World List of Cycads. A reassessment by J.D. Bösenberg was published in version 2023-1 of the Red List (reference found on Crossref); the Red List data relayed by GBIF still give the category as EN (consulted on 24 October 2026), but its criteria could not be checked, the Red List itself being inaccessible.

This listing contrasts with the view of Lindström et al. (2008), who recommended Least Concern. Cycas chamberlainii had been reported destroyed in its original habitat by clearing for agriculture and given the category “V” in the 1997 IUCN Red List of Threatened Plants, and Donaldson (2003) had rated it Data Deficient; the authors observed instead that the species remained abundant, in healthy populations, on Mount Arayat and in many other montane forests.

In the Philippines, the scale insect Aulacaspis yasumatsui is spreading fast and devastating cultivated cycads on Luzon, Negros and Panay; in 2008 its presence in wild populations had not been confirmed, but its spread would be serious for the endemic species (Lindström et al. 2008).

Like every species in the genus except Cycas beddomei, Cycas riuminiana is listed in CITES Appendix II, where the family Cycadaceae has been included since 4 February 1977. The listing carries annotation #4 (CoP20 version, in force since 5 March 2026): seeds, pollen, seedlings or tissue cultures obtained in vitro and transported in sterile containers, and cut flowers of artificially propagated plants, are not subject to CITES, whereas international trade in the plants themselves requires an export permit. The United Kingdom, the United States and Australia apply CITES through their own national legislation; in the European Union the species is in Annex B of Regulation (EC) No 338/97, whose annexes in force are set by Commission Regulation (EU) 2026/1383, applicable since 29 June 2026. Species+, the official CITES database, names the species and its synonyms and confirms this status.

This general information does not replace the official texts: check the rules in force before buying or exchanging plants, ask the seller for proof of provenance and prefer plants raised from seed in cultivation.

Growing Cycas riuminiana

In short: grown in the Philippines, in villages and at the Makiling Botanic Gardens, and present in several American and Australian botanic gardens, but no institution has published growing advice. It is a plant of tropical montane forest, and any advice beyond that is a deduction.

Outdoor and in-ground cultivation

Outdoors, it can only be considered in frost-free tropical or warm subtropical climates; the American gardens that declare it are in southern Florida, coastal southern California and Hawaii, though whether their plants grow in the open is not stated. Its habitat, closed evergreen forest on steep, well-drained slopes, suggests light shade when young and a free-draining soil, but this is a deduction from the wild, not a tested recommendation.

Container cultivation

In the United Kingdom and other temperate regions, it is a plant for a heated glasshouse, in a pot; its eventual height of up to 8 m limits it to large glasshouses. No Mediterranean experience is available: the French forum Fous de palmiers and the Italian forum Tropicamente gave no usable growing report, and the Jardin zoologique tropical at La Londe-les-Maures, in the south of France, has published no observation on it.

In cultivation in the UK, US and Australia

In short: present in several gardens in the United States and Australia, sometimes under the name Cycas chamberlainii.

  • United States: the online catalogue of Montgomery Botanical Center (Coral Gables, Florida) lists four accessions: 77963 (probably 1977, going by the numbering), 951201 (1995), 20060620 (2006) and 20150362 (2015); a search under chamberlainii leads to the same record. In the BGCI PlantSearch database (consulted on 24 October 2026), Lotusland (near Santa Barbara, California) and the Huntington (San Marino, California) declare it under Cycas riuminiana, and Fairchild Tropical Botanic Garden (Florida) and Honolulu Botanical Gardens (Hawaii) under Cycas chamberlainii.
  • Australia: the Royal Botanic Garden Sydney declares it in BGCI and lists it in its online catalogue (Garden Explorer, consulted on 19 October 2026; out of service on 24 October); the Cairns Botanic Gardens declare it under Cycas chamberlainii.
  • United Kingdom: no garden declares it in BGCI, and no other record was found.

Outside these countries, BGCI also lists gardens in the Philippines (Northwestern University Ecological Park and Botanic Gardens, Laoag), China, South Africa, Singapore and the Netherlands (Hortus Botanicus Amsterdam). A BGCI entry shows that a garden has declared the species at some point, not that a plant is alive there today. No first-hand report from a private grower in these countries could be read; PalmTalk and Dave’s Garden could not be consulted.

Propagation

Like all Cycas, Cycas riuminiana is dioecious: a male and a female plant are needed for fertile seed. Sowing is the only documented method, through the seed distributed in the 1990s; no germination time or rate has been published. Seeds are exempt from CITES under annotation #4.

Pests and diseases

The main documented threat is the scale insect Aulacaspis yasumatsui, which is devastating cultivated cycads on Luzon (Lindström et al. 2008). No other pest or disease specific to the species is documented.

Cold hardiness

No cold-tolerance data exist for Cycas riuminiana. Luzon has a tropical climate without frost at the altitudes where it grows, and nothing suggests that the plant can take frost.

Mediterranean and European experience

No cultivation result has been published in Europe, in the open ground or in a pot, and no dated frost episode concerns the species. A search of the French forum Fous de palmiers and the Italian forum Tropicamente, under its different names, found no report of cold tolerance for it.

United Kingdom, United States and Australia

No cold reading and no dated growing report were found, either on forums or from botanic gardens. The British nursery Trebrown rates it USDA zone 9b (average annual minimum of −3.9 to −1.1 °C, or 25 to 30 °F), a commercial rating not backed by any published growing observation. The American gardens that declare it, in southern Florida, Hawaii and coastal California, do not say whether their plants grow outdoors.

Toxicity and precautions

No toxicity analysis specific to Cycas riuminiana has been found. The risk is, however, well documented in the genus: Cycas tissues, and the seeds above all, contain cycasin, which is converted during digestion into methylazoxymethanol, toxic to the liver and nervous system, along with a neurotoxic amino acid, BMAA. The ASPCA lists the sago palm (Cycas revoluta) as poisonous to dogs, cats and horses. Until proven otherwise, treat the plant as poisonous: keep seeds and leaves out of reach of children and pets, and wear gloves to clean the seeds. If any part is swallowed, contact a poison centre, a doctor or a vet straight away.

Traditional uses

The Makiling Botanic Gardens list uses of pitogo: a seed that is edible once properly processed, leaves eaten as a vegetable, starch (sago) extracted from the trunk, and medicinal uses of the resin, seeds, bark and leaves; they do not cite their sources. The Tagalog name pitógo, reserved for the seed, reflects its use. Given the toxicity of cycads, these mentions are in no way a recommendation.

Frequently asked questions

Are Cycas riuminiana and Cycas chamberlainii the same plant?

Yes. Cycas chamberlainii, described in 1925 from the plants of Mount Arayat, is a synonym of Cycas riuminiana, and some gardens still list the species under that name.

What is pitogo?

It is the Tagalog name for the seed of Cycas riuminiana, often extended to the whole plant; it may also refer to other Philippine cycads.

Where does Cycas riuminiana grow?

On Luzon and in the Batanes Islands, in the Philippines, in closed forest on ridges and mountain slopes, notably on Mount Arayat and in the Sierra Madre.

Is it endangered?

Yes, according to the IUCN, which has listed it as Endangered since 2010; some botanists nevertheless considered it still abundant in 2008.

Is it a subspecies of Cycas circinalis?

No. Schuster treated it that way in 1932, but it is a distinct species; Cycas circinalis grows in India.

Can it be grown outdoors in the UK?

No. No cold data exist and it is a plant of tropical forest: grow it in a pot in a heated glasshouse.

Is it poisonous?

It must be assumed so. Its seeds are eaten in the Philippines after processing, but cycads contain dangerous toxins, especially in the seeds.

Further reading on Succulentes

Sources

Reference sites

Bibliography

  • Lindström, A.J., Hill, K.D. & Stanberg, L.C. (2008). The genus Cycas (Cycadaceae) in the Philippines. Telopea 12(1): 119–145. doi:10.7751/telopea20085805 [Description, synonymy, typification, history, vernacular names, range, status (pp. 132–134); full text consulted.]
  • Hill, K.D. & Stanberg, L.C. (2009). Notes on Cycas truncata de Laub. and related matters. Telopea 12(3): 447–450. doi:10.7751/telopea20095832 [Illegitimacy of Cycas truncata and placement of its material in Cycas riuminiana; full text consulted.]
  • Regel, E. (1863). Cycas riuminiana Porte. Gartenflora 12: 16–17. [Original description; not consulted (Biodiversity Heritage Library inaccessible), cited after Lindström et al. (2008).]
  • Brown, W.H. & Kienholz, R. (1925). [Cycas chamberlainii]. Philippine Journal of Science 26: 47–48. [Description of the synonym; not consulted, cited after The World List of Cycads.]
  • de Laubenfels, D.J. & Adema, F. (1998). A taxonomic revision of the genera Cycas and Epicycas gen. nov. (Cycadaceae). Blumea 43(2): 351–400. [Broad circumscription of Cycas riuminiana (pp. 382–383), lectotype at K; full text consulted.]
  • Agoo, E.M.G., Madulid, D.A., Linis, V.C. & Sambale, E. (2010). Cycas riuminiana. The IUCN Red List of Threatened Species 2010: e.T42095A10630183. doi:10.2305/IUCN.UK.2010-3.RLTS.T42095A10630183.en [Assessment cited by The World List of Cycads; Red List page not consulted (access blocked).]
  • Bösenberg, J.D. (2023). Cycas riuminiana. The IUCN Red List of Threatened Species: e.T239047689A69155789. doi:10.2305/IUCN.UK.2023-1.RLTS.T239047689A69155789.en [Reassessment; reference found on Crossref, EN category relayed by GBIF; criteria not checked.]
  • Haynes, J.L. (2022). Etymological compendium of cycad names. Phytotaxa 550(1): 1–31. doi:10.11646/phytotaxa.550.1.1 [Source of the etymologies taken up by The World List of Cycads; not consulted directly.]
  • Calonje, M., Stevenson, D.W. & Osborne, R. (2026). The World List of Cycads, version 2026.08.15. Montgomery Botanical Center, Coral Gables. doi:10.5281/zenodo.21958524 [Reference checklist; consulted directly.]