Ovulate cone and seed biology of Wollemia nobilis (Araucariaceae) and comparison with Agathis microstachya and Araucaria cunninghamii
Geoffrey E. Burrows
A *
A
Abstract
Most gymnosperms are dioecious (no self-pollination). It was not known if Wollemia nobilis (monoecious) could produce viable seeds via self-pollination.
In the nearly 30 years since its scientific discovery Wollemia nobilis (Araucariaceae) has been the focus of considerable scientific attention. While this includes several aspects of sexual reproduction, many features of ovulate cone morphology and seed biology have not been investigated.
Various aspects of ovulate cone morphology were quantified, as were seed morphology and germination (e.g. seed moisture content and rate of imbibition), in material from an isolated tree of Wollemia nobilis. Seeds of Agathis microstachya and Araucaria cunninghamii were also examined to allow comparisons across the Araucariaceae.
In Wollemia nobilis most seeds were empty (no formation of a megagametophyte and embryo (M + E)). Empty and filled seeds were morphologically very similar. On average, the fresh weights (FW) of empty and filled seeds were 6.2 and 33.1 mg, respectively. On average, the FW of the M + E was 25.8 mg (78% of seed mass, the other 22% was testa). The average moisture content (FW basis) of the testa and the M + E were 9.6% and 7.0%, respectively. The M + E imbibed water relatively slowly and imbibed, on average, to ~110% increase in FW after 48 h. In Agathis robusta and Wollemia nobilis the seeds separated freely from the cone scales. In Araucaria cunninghamii the M + E was an integral part of the bract/scale complex.
The seeds examined in this study came from an isolated, almost certainly self-fertilised tree. The seeds were of approximately the same dimensions as those from the wild populations of Wollemia nobilis, while average filled seed FW was greater and less variable. The filled seeds had a high viability and an excised M + E could germinate rapidly. This study shows that Wollemia nobilis can produce large, viable seeds via self-fertilisation. Successful self-fertilisation may be a factor in the low genetic diversity detected in the wild population.
Based on evidence from a single tree it would appear that Wollemia nobilis can produce large, viable, vigorous seeds via self-fertilisation. This has implications for the population structure of this species.
Keywords: germination, imbibition, megagametophyte, moisture content, monoecious, nucellus, self-fertilisation, Wollemi pine.
References
Abate NB, Degu HD, Kalousová M, Abebe T (2025) Inbreeding depression manifested in progeny from fragmented populations of the wind-pollinated dioecious conifer Afrocarpus gracilior (Pilg.) C. N. Page. Ecology and Evolution 15(2), e70903.
| Crossref | Google Scholar |
Angkotta JC, Nugroho JD, Sinaga NI (2022) Characterization of cones and seeds of damar (Agathis labillardieri) from plantation in Klasaman, Sorong. Jurnal Sylva Lestari 10(1), 107-115.
| Crossref | Google Scholar |
Ashmore SE, Hamilton KN, Offord CA (2011) Conservation technologies for safeguarding and restoring threatened flora: case studies from Eastern Australia. In Vitro Cellular & Developmental Biology – Plant 47, 99-109.
| Crossref | Google Scholar |
Bonner FT (1990) Storage of seeds: potential and limitations for germplasm conservation. Forest Ecology and Management 35(1–2), 35-43.
| Crossref | Google Scholar |
Briggs BG (2000) What is significant – the Wollemi pine or the southern rushes? Annals of the Missouri Botanical Garden 87(1), 72-80.
| Crossref | Google Scholar |
Burrows GE, Heady RD, Smith JP (2017) Substantial resource reallocation during germination of Araucaria bidwillii (bunya pine), an Australian rainforest conifer with large seeds and cryptogeal germination. Trees 31(1), 115-124.
| Crossref | Google Scholar |
Cantrill DJ, Raine JI (2006) Wairarapaia mildenhallii gen. et sp. nov., a new Araucarian cone related to Wollemia from the Cretaceous (Albian-Cenomanian) of New Zealand. International Journal of Plant Sciences 167(6), 1259-1269.
| Crossref | Google Scholar |
Chambers TC, Drinnan AN, McLoughlin S (1998) Some morphological features of Wollemi pine (Wollemia nobilis: Araucariaceae) and their comparison to Cretaceous plant fossils. International Journal of Plant Sciences 159(1), 160-171.
| Crossref | Google Scholar |
Dettmann ME, Clifford HT, Peters M (2012) Emwadea microcarpa gen. et sp. nov. – anatomically preserved araucarian seed cones from the Winton Formation (late Albian), western Queensland, Australia. Alcheringa: An Australasian Journal of Palaeontology 36(2), 217-237.
| Crossref | Google Scholar |
Dickie JB, Smith RD (1995) Observations on the survival of seeds of Agathis spp. stored at low moisture contents and temperatures. Seed Science Research 5(1), 5-14.
| Crossref | Google Scholar |
Dörken VM, Rudall PJ (2019) Structure and abnormalities in cones of the Wollemi pine (Wollemia nobilis). Kew Bulletin 74, 3.
| Crossref | Google Scholar |
Escapa IH, Catalano SA (2013) Phylogenetic analysis of Araucariaceae: integrating molecules, morphology, and fossils. International Journal of Plant Sciences 174(8), 1153-1170.
| Crossref | Google Scholar |
Gelbart G, von Aderkas P (2002) Ovular secretions as part of pollination mechanisms in conifers. Annals of Forest Science 59(4), 345-357.
| Crossref | Google Scholar |
Greenfield A, McPherson H, Auld T, Delaney S, Offord CA, Van der Merwe M, Yap J-YS, Rossetto M (2016) Whole-chloroplast analysis as an approach for fine-tuning the preservation of a highly charismatic but critically endangered species, Wollemia nobilis (Araucariaceae). Australian Journal of Botany 64(8), 654-658.
| Crossref | Google Scholar |
Hill KD (1997) Architecture of the Wollemi pine (Wollemia nobilis, Araucariaceae), a unique combination of model and reiteration. Australian Journal of Botany 45(5), 817-826.
| Crossref | Google Scholar |
Hill KD (2003) The wollemi pine, another living fossil? Acta Horticulturae 615, 157-164.
| Crossref | Google Scholar |
Huang R, Zeng W, Deng H, Hu D, Wang R, Zheng H (2022) Inbreeding in Chinese fir: insight into the rare self-fertilizing event from a genetic view. Genes 13(11), 2105.
| Crossref | Google Scholar |
Jones WG, Hill KD, Allen JM (1995) Wollemia nobilis, a new living Australian genus and species in the Araucariaceae. Telopea 6(2–3), 173-176.
| Crossref | Google Scholar |
Kettle CJ, Hollingsworth PM, Jaffré T, Moran B, Ennos RA (2007) Identifying the early genetic consequences of habitat degradation in a highly threatened tropical conifer, Araucaria nemorosa Laubenfels. Molecular Ecology 16(17), 3581-3591.
| Crossref | Google Scholar | PubMed |
Kettle CJ, Ennos RA, Jaffré T, Gardner M, Hollingsworth PM (2008) Cryptic genetic bottlenecks during restoration of an endangered tropical conifer. Biological Conservation 141(8), 1953-1961.
| Crossref | Google Scholar |
Martínez LCA, Huacallo EP, Pujana RR, Padula H (2020) A new megaflora (leaves and reproductive structures) from the Huancane Formation (Lower Cretaceous), Peru. Cretaceous Research 110, 104426.
| Crossref | Google Scholar |
McLoughlin S, Vajda V (2005) Ancient wollemi pines resurgent. American Scientist 93(6), 540-547.
| Crossref | Google Scholar |
Ng MCH, Tran VH, Duke RK, Offord CA, Meagher PF, Cui PH, Duke CC (2024) Lipid profile of fresh and aged Wollemia nobilis seeds: omega-3 epoxylipid in older stored seeds. Lipidology 1(2), 92-104.
| Crossref | Google Scholar |
Offord CA, Meagher PF (2001) Effects of temperature, light and stratification on seed germination of Wollemi pine (Wollemia nobilis, Araucariaceae). Australian Journal of Botany 49(6), 699-704.
| Crossref | Google Scholar |
Offord CA, Porter CL, Meagher PF, Errington G (1999) Sexual reproduction and early plant growth of the Wollemi pine (Wollemia nobilis), a rare and threatened Australian conifer. Annals of Botany 84(1), 1-9.
| Crossref | Google Scholar |
Pastoriza-Piñol J (2007) 590. Wollemia nobilis. Curtis’s Botanical Magazine 24(3), 155-161.
| Crossref | Google Scholar |
Peakall R, Ebert D, Scott LJ, Meagher PF, Offord CA (2003) Comparative genetic study confirms exceptionally low genetic variation in the ancient and endangered relictual conifer, Wollemia nobilis (Araucariaceae). Molecular Ecology 12(9), 2331-2343.
| Crossref | Google Scholar | PubMed |
Sanderson KD (1998) Effect of storage conditions on viability of wind-dispersed seeds of some cabinet timber species from Australian tropical rainforests. Australian Forestry 61(2), 76-81.
| Crossref | Google Scholar |
Sorensen FC (1982) The roles of polyembryony and embryo viability in the genetic system of conifers. Evolution 36(4), 725-733.
| Crossref | Google Scholar | PubMed |
Stockey RA, Rothwell GW (2020) Diversification of crown group Araucaria: the role of Araucaria famii sp. nov. in the late Cretaceous (Campanian) radiation of Araucariaceae in the Northern Hemisphere. American Journal of Botany 107(7), 1072-1093.
| Crossref | Google Scholar |
Timchenko AS, Sorokin AN, Zdravchev NS, Bobrov AVFC, Romanov MS (2020) Comparative seed coat anatomy of the genus Wollemia (Araucariaceae). Problems of Botany of Southern Siberia and Mongolia 19(2), 134-139.
| Crossref | Google Scholar |
Tompsett PB (1982) The effect of desiccation on the longevity of seeds of Araucaria hunsteinii and A. cunninghamii. Annals of Botany 50(5), 693-704.
| Crossref | Google Scholar |
Tompsett PB (1984) Desiccation studies in relation to the storage of Araucaria seed. Annals of Applied Biology 105(3), 581-586.
| Crossref | Google Scholar |
Walas L, Mandryk W, Thomas PA, Tyrala-Wierucka Z, Iszkulo G (2018) Sexual systems in gymnosperms: a review. Basic and Applied Ecology 31, 1-9.
| Crossref | Google Scholar |
Zimmer HC, Meagher PF, Auld TD, Plaza J, Offord CA (2015) Year-to-year variation in cone production in Wollemia nobilis (Wollemi Pine). Cunninghamia 15, 79-85.
| Google Scholar |
