Cycas saxatilis

Cycas saxatilis is a cliff-dwelling cycad of the island of Palawan, in the Philippines, which grows without soil in the cracks of vertical limestone cliffs in the St Paul’s massif, its stems hanging over the void. This species of the genus Cycas was described in 2008 by K.D. Hill and A.J. Lindström, who placed it with Cycas wadei and Cycas curranii in section Wadeae, a small group found only in the Philippines. It remains poorly known: its authors never saw its female cones or seeds. The IUCN lists it as Vulnerable.

Key facts about Cycas saxatilis

  • Accepted name: Cycas saxatilis K.D.Hill & A.Lindstr. (2008), accepted by The World List of Cycads (version 2026.08.15) and by GBIF; the World Checklist of Vascular Plants (WCVP), on which POWO is based, also accepts it (consulted through GBIF on 31 October 2026)
  • Former names and synonyms: none
  • Family: Cycadaceae, order Cycadales
  • Common names: none attested, in English or in a Philippine language
  • Natural range: Philippines, island of Palawan (limestone massif of Mount St Paul)
  • IUCN status: Vulnerable (VU, criterion D2 according to The World List of Cycads), assessment by J.D. Bösenberg (2010), reassessed by A. Lindström in Red List version 2023-1; VU according to GBIF
  • CITES and other protection: CITES Appendix II (seeds exempt under annotation #4); Annex B in the European Union; most of its range lies within the St Paul’s Bay National Park, according to Lindström et al. (2008)
  • Documented hardiness: no data (see Cold hardiness)
  • Light and soil: in the wild, crevices in vertical limestone cliffs, without soil, in exposed places; no cultivation data
  • Habit and adult size: stems 0.5 to 4 m long and 20 to 25 cm across, hanging from the cliffs; leaves 1.6 to 1.9 m long
  • In the UK, US and Australia: no botanic garden record
  • Toxicity: no data specific to the species; treat it as poisonous, like all Cycas (see Toxicity and precautions)

How to recognise Cycas saxatilis

Its habitat is the first clue: no other cycad in the region hangs from bare limestone cliffs. According to Lindström, Hill and Stanberg (2008), it is also set apart by its narrow, elongated male cones and by soft microsporophylls without an apical spine. In their key to the Philippine cycads, it is separated from Cycas wadei by its broader leaflets, 10 to 14 mm wide. The key published by Agoo and Madulid in 2012 attributes ribbed seeds no more than 40 mm long to it, although no description of the seeds has ever been published. The description below follows the original publication.

  • Stems: tree-like, 0.5 to 4 m long and 20 to 25 cm in diameter at their narrowest point, growing on bare vertical cliffs, not strongly swollen at the base; bark thin and smooth.
  • Leaves: bright green and highly glossy, 1.6 to 1.9 m long, slightly keeled or flat in section, with 170 to 380 leaflets, ending in a pair of leaflets.
  • Petiole: 40 to 60 cm long (25 to 35% of the leaf), hairless, spiny for 50 to 90% of its length.
  • Median leaflets: 22 to 34 cm long and 9 to 12 mm wide, strongly two-toned, with flat or slightly recurved margins and a pointed but not spiny tip, set 10 to 17 mm apart.
  • Male cones: ovoid, cream or green, about 49 cm long and 5 cm across; the microsporophylls are soft, not thickened, with a rudimentary, upturned apical spine.
  • Megasporophylls and seeds: not seen by the authors of the species.

The key gives leaflets 10 to 14 mm wide while the description gives 9 to 12 mm. More curiously, the Latin diagnosis mentions reduced megasporophylls with elongated apical spines, although the English description states that neither megasporophylls nor seeds were seen: the female plant remains, in practice, undescribed.

Hybrids

No hybrid, natural or horticultural, is documented for this species.

Possible confusion

The type specimen, made up of leaves and a male cone, most closely resembles Cycas curranii, another Palawan species. It was field observation that led to separating the two: Cycas curranii is a tall, upright cycad of rainforest on serpentine soils, whereas the plants of St Paul’s Bay hang from exposed limestone cliffs (Lindström et al. 2008). Cycas wadei, from the island of Culion, has narrow leaflets, 3 to 8 mm wide, and more strongly keeled leaves. Palawan also has Cycas aenigma, known only from cultivated plants, which belongs to another section; in the key of Agoo and Madulid (2012), its seeds are not ribbed.

Taxonomy

Cycas saxatilis is a name accepted by The World List of Cycads and by GBIF; the World Checklist of Vascular Plants (WCVP), on which POWO is based, also accepts it (consulted through GBIF on 31 October 2026). K.D. Hill and A.J. Lindström described it in 2008 in the revision of the Philippine cycads by Lindström, Hill and Stanberg (Telopea 12(1): 128–129, fig. 2), from a specimen collected by Podzorski on 6 April 1984 on a major limestone outcrop south-east of St Paul’s Bay, on Palawan, where it hung from the cliff face (Podzorski SMHI 2035; holotype at the Leiden herbarium, L).

The authors placed it in section Wadeae, created in the same paper, with Cycas wadei and Cycas curranii. This section, isolated within the genus and confined to the Philippines, is defined by soft, waxy male cones and microsporophylls, megasporophylls with a comb-like tip, hairless ovules and yellow seeds whose hard shell carries strong lengthwise ribs. Lindström et al. regard it as a relict group, related to the groups of mainland Asia and perhaps isolated by the drift of land masses early in the Tertiary. As the seeds of Cycas saxatilis have not been described, its place in the section rests on the characters of the leaves and male cone.

Etymology and history

The epithet comes from the Latin saxatilis, “dwelling among rocks”, in reference to its soil-free cliff-face habitat (Lindström et al. 2008; Haynes 2022).

The species was recognised from Podzorski’s collection of 1984 and from an observation by Hill and Lindström along the road to St Paul’s Bay on 25 June 2001, recorded without a herbarium specimen; the habitat sketch in the original publication is drawn from a slide taken that day. No introduction into cultivation is documented.

Common names

No English common name is attested, and no name in a Philippine language is attested for this species.

In the wild

Cycas saxatilis is known only from the limestone outcrops of the Mount St Paul massif, on Palawan. It grows in crevices in vertical limestone cliffs with no soil, in exposed places (Lindström et al. 2008). The massif is fairly extensive, and plants are abundant there, in large, undisturbed populations in the most inaccessible sites. Pollination and phenology are not documented.

On Palawan, the cycad scale Aulacaspis yasumatsui, which seriously affects cultivated cycads elsewhere in the Philippines, seems to be kept in check by native predators (Lindström et al. 2008).

Conservation status and regulation

The IUCN lists Cycas saxatilis as Vulnerable (VU) under criterion D2, which applies to species known from a very small number of locations, in the assessment by J.D. Bösenberg (2010) cited by The World List of Cycads. A reassessment by A. Lindström 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 VU (consulted on 24 October 2026), but these data do not give its criteria. When they described the species, Lindström et al. (2008) recommended Least Concern instead: although it is known from a single locality, it is abundant in an extensive massif, and most of its range lies within the St Paul’s Bay National Park. Agoo and Madulid (2012) recall the Vulnerable status.

Like every species in the genus except Cycas beddomei, Cycas saxatilis falls under CITES Appendix II, where the family Cycadaceae has been included since 4 February 1977. Annotation #4 (CoP20 version, in force since 5 March 2026) exempts seeds, pollen, seedlings and tissue cultures obtained in vitro and transported in sterile containers, and cut flowers of artificially propagated plants; international trade in the plants themselves requires an export permit. The United Kingdom, the United States and Australia apply CITES through their own legislation; in the European Union the species is in Annex B of Regulation (EC) No 338/97, as set by Commission Regulation (EU) 2026/1383, applicable since 29 June 2026. Species+, the official CITES database, names the species and confirms this status. This information was checked in October 2026 and does not replace the official texts: check the rules in force, ask for proof of origin and prefer plants raised from seed in cultivation.

Growing Cycas saxatilis

In short: no institution consulted documents it in cultivation and no grower’s report has been published.

Outdoor and in-ground cultivation

The points below are deductions from its habitat, not documented results. A plant that lives on bare limestone cliffs, without soil, presumably needs perfect drainage, and its natural position, hanging from vertical rock in full exposure, suggests that a rockery or a wall pocket would suit it better than flat ground. Palawan has a tropical climate without frost: outdoors, only frost-free tropical climates can be considered.

Container cultivation

In the United Kingdom and other temperate regions, the only realistic option would be a pot in a heated glasshouse, presumably in a very open, mineral mix. No European experience exists.

In cultivation in the UK, US and Australia

In short: no record. The species does not appear in the BGCI PlantSearch database or in the online catalogue of Montgomery Botanical Center (both consulted on 24 October 2026), nor in the online catalogues of British, American and Australian gardens (October 2026). No report from a private grower is documented.

Propagation

The plant is dioecious: seed requires a male and a female plant. No germination data exist, since the seeds have not been described. Seeds are exempt from CITES under annotation #4; look only for seed of legal, documented origin.

Pests and diseases

No pest or disease specific to the species is documented. In the wild on Palawan, the cycad scale appears to be controlled by native predators (see In the wild). In cultivation, as with any Cycas, scales could attack it, and overwatering or poor drainage would rot the trunk and roots.

Cold hardiness

No cold-tolerance data exist for Cycas saxatilis. Palawan has a frost-free tropical climate, 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 this species.

United Kingdom, United States and Australia

No cold reading is documented in any country, and no hardiness zone can be given on the basis of a documented trial. Treat it as a frost-tender glasshouse plant outside the tropics.

Toxicity and precautions

No toxicity study specific to Cycas saxatilis has been published, but the risk is 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. In the absence of evidence to the contrary, treat this species as poisonous: keep seeds and leaves out of reach of children and animals and wear gloves to handle seeds. If any part is swallowed, contact a poison centre, a doctor or a vet straight away.

Traditional uses

No use is documented for this species.

Frequently asked questions

What does saxatilis mean?

“Dwelling among rocks” in Latin: the species grows in the cracks of limestone cliffs, without soil.

Where does Cycas saxatilis grow?

Only on the island of Palawan, in the Philippines, on the cliffs of the Mount St Paul limestone massif.

How does it differ from Cycas curranii?

Cycas curranii is a tall, upright cycad of forest on serpentine soils; Cycas saxatilis hangs from exposed limestone cliffs and has narrower male cones.

What is section Wadeae?

A small group of three cycads confined to the Philippines, with soft, waxy male cones and ribbed seeds.

Is it endangered?

The IUCN lists it as Vulnerable because it is known from a single massif, a category kept in the reassessment published in 2023; its authors nevertheless found it abundant and largely protected.

Is it found in cultivation?

No cultivated plant is documented, in botanic gardens or elsewhere.

Is it poisonous?

It must be assumed so. No analysis specific to the species exists, but all the cycads studied 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 [Original description (pp. 128–129, fig. 2), section Wadeae, recommended status, cycad scale on Palawan.]
  • Agoo, E.M.G. & Madulid, D.A. (2012). Cycas sancti-lasallei (Cycadaceae), a new species from the Philippines. Blumea 57(2): 131–133. doi:10.3767/000651912X657503 [Key to the Philippine cycads, Vulnerable status.]
  • Bösenberg, J.D. (2010). Cycas saxatilis. The IUCN Red List of Threatened Species: e.T178864A7630617. doi:10.2305/IUCN.UK.2010-3.RLTS.T178864A7630617.en [Red List assessment; reference found on The World List of Cycads and Crossref.]
  • Lindström, A. (2023). Cycas saxatilis. The IUCN Red List of Threatened Species: e.T178864A69156279. doi:10.2305/IUCN.UK.2023-1.RLTS.T178864A69156279.en [Reassessment; reference found on Crossref, VU category relayed by GBIF.]
  • 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 given by The World List of Cycads.]
  • 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.]