Ceratopetalum

Ceratopetalum
Ceratopetalum gummiferum showing flowers, foliage and fruit, all typical of the genus.
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Embryophytes
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Oxalidales
Family: Cunoniaceae
Genus: Ceratopetalum
Sm.[1][2]
Species

See text

Ceratopetalum is a genus of nine species of plants in the family Cunoniaceae. They are native to eastern Australia (eight species) and New Guinea (one species). They are trees or large shrubs of rainforest or moist sclerophyll forest, some producing useful timber. Fossil records suggest the range of the genus extended to the Americas in the past.

Description

The genus is characterised by leaves that are opposite and decussate; are either simple (undivided) or with three leaflets; have paired interpetiolar stipules; are usually glabrous and without domatia.[3]: 654 [4]

The inflorescences are terminal (sometimes axillary) with decussate branching. Flowers have both male and female organs (bisexual); have either four or five sepals; have no petals except for C. gummiferum; have two whorls of stamens, the outer whorl opposite the sepals and the inner whorl between the sepals; have an ovary with two (rarely three) carpels; have an annular nectary disc surrounding the ovary.[3]: 656 [4]

The fruit are distinctive for the genus. They are indehiscent and the stamens and sepals both remain with the fruit after it has been shed from the tree. They have been variously labelled by different botanists—as a nut by Adolf Engler, Gwen Harden and others, and as a capsule by Bernard Hyland, and as a samara by William C. Dickison.[3]: 656–660 [4]

Distribution and habitat

Species in this genus are distributed in three disjunct regions. Both C. aptetalum and C. gummiferum are found in eastern New South Wales and southeast Queensland, and C. tetrapterum occurs in New Guinea and the Bismarck Archipelago. The remaining six species are found at altitude in a small part of northeast Queensland.[3]: 651–652  All species grow in rainforest, except C. gummiferum which inhabits wet sclerophyll forest, and C. apetalum which inhabits both forest types.[3]: 662, 664 

Taxonomy

The genus Ceratopetalum was established by James Edward Smith in his book A Specimen of the Botany of New Holland, published in 1793, which contained the first description of C. gummiferum.[5][6]

The genus is placed in the tribe Schizomerieae, alongside the genera Schizomeria, Anodopetalum and Platylophus.[3]: 651 [7]: 373 

Speciation in North Queensland

Allopatric speciation is a process in which the population of a species is divided permanently by a geographical barrier which prevents the two subpopulations from interbreeding. Each subpopulation then evolves separately and eventually forms a new species. It is believed that this process is responsible for the diversity of species in northeast Queensland. Evidence shows that during the last glacial cycle (18,000 YBP), areas suitable for Certopetalum contracted to mountain peaks where higher rainfall persisted, and it has been suggested that this resulted in the speciation seen today.[3]: 671 

Extant species

Nine species are recognised as of May 2026:[2]

Fossil species

  • †Ceratopetalum edgardoromeroi – Eocene, South America[8]
  • †Ceratopetalum maslinensis – Eocene, South Australia[9]
  • †Ceratopetalum suciensis – Eocene, North America[10]
  • †Ceratopetalum westermannii – Miocene, New South Wales[9]
  • †Ceratopetalum wilkinsonii – Eocene, New South Wales[8]

References

  1. ↑ "Ceratopetalum Sm". Australian Plant Name Index (APNI). Centre for Australian National Biodiversity Research, Australian Government. Retrieved 16 May 2026.
  2. 1 2 "Ceratopetalum Sm". Plants of the World Online. Royal Botanic Gardens, Kew. 2026. Retrieved 13 May 2026.
  3. 1 2 3 4 5 6 7 Rozefelds, Andrew C.; Barnes, Richard W. (2002). "The Systematic and Biogeographical Relationships of Ceratopetalum (Cunoniaceae) in Australia and New Guinea". International Journal of Plant Sciences. 163 (4): 651–673. Bibcode:2002IJPlS.163..651R. doi:10.1086/339716.
  4. 1 2 3 Bradford, J.C.; Fortune-Hopkins, H.C.; Barnes, R.W. (2004). "Cunoniaceae". In Kubitzki, Klaus (ed.). Flowering Plants, Celastrales, Oxalidales, Rosales, Cornales, Ericales. The Families and Genera of Vascular Plants. Vol. 6. Berlin: Springer. p. 103. doi:10.1007/978-3-662-07257-8. ISBN 978-3-642-05714-4.
  5. ↑ "Ceratopetalum Sm., Spec. Bot. New Holland 1: 9 (t. 3) (1793)". International Plant Names Index (IPNI). Royal Botanic Gardens, Kew. 2026. Retrieved 18 May 2026.
  6. ↑ Smith, James Edward (1793). A Specimen of the Botany of New Holland (in English and Latin). Illustrated by James Sowerby. London: J. Sowerby. pp. 8–12.
  7. ↑ Bradford, Jason C.; Barnes, Richard W. (2001). "Phylogenetics and Classification of Cunoniaceae (Oxalidales) Using Chloroplast DNA Sequences and Morphology". Systematic Botany. 26 (2): 354–385.
  8. 1 2 Jud, Nathan A.; Gandolfo, Maria A.; Iglesias, Ari; Wilf, Peter (2018). "Fossil flowers from the early Palaeocene of Patagonia, Argentina, with affinity to Schizomerieae (Cunoniaceae)". Annals of Botany. 121 (3): 431–442. doi:10.1093/aob/mcx173. PMC 5838809. PMID 29309506.
  9. 1 2 Barnes, Richard W.; Hill, Robert S. (1999). "Ceratopetalum fruits from Australian cainozoic sediments and their significance for petal evolution in the genus". Australian Systematic Botany. 12 (5): 635–645. doi:10.1071/SB98014.
  10. ↑ Tang, Keana K.; Smith, Selena Y.; Atkinson, Brian A. (2022). "Extending beyond Gondwana: Cretaceous Cunoniaceae from western North America". New Phytologist. 234 (2): 704–718. Bibcode:2022NewPh.234..704T. doi:10.1111/nph.17976. hdl:2027.42/172025.
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