Register      Login
Australian Journal of Botany Australian Journal of Botany Society
Southern hemisphere botanical ecosystems
RESEARCH ARTICLE

Seed germination and unusual serotiny in two species of Conospermum from fire-prone vegetation in Western Australia

Xiaoying Zhao A C and P. G. Ladd B
+ Author Affiliations
- Author Affiliations

A School of Life Science, Xinjiang Normal University, Urumqi, 830054, China.

B School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA 6150, Australia.

C Corresponding author. Email: zzhaoxy@163.com

Australian Journal of Botany 62(6) 511-517 https://doi.org/10.1071/BT14237
Submitted: 10 September 2014  Accepted: 10 November 2014   Published: 23 December 2014

Abstract

Serotiny is a mechanism for storing propagules on plants, so that seed dispersal can be maximised after the death of aerial parts of plants or to take advantage of conditions beneficial to establishment. In fire-prone vegetation, regeneration of new plants after fire is mostly from seeds that are stored in the soil or on the plant. These traits are generally consistent within a genus. However, in Conospermum, a genus of shrubs that mostly occur in fire-prone vegetation and in which most species have soil-stored seeds, two species exhibit an unusual serotinous structure. We examined the morphology and anatomy of inflorescences and infructescences of C. capitatum and C. petiolare that were collected from natural vegetation in south-western Western Australia. Inflorescence and infructescence axes were sectioned and examined microscopically, fresh infructescences were heated in an oven to various temperatures for 2 min and the fruits from them sown in a germination trial. Some fruits were also treated with smoke chemicals. Both species have a low, dense growth form and retain the seed-like fruits in a serotinous structure formed by enlargement of the cortical cells of the inflorescence axis after flowering. The fruits can be effectively released from the plant only if the foliage is removed by a fire. For both species, the infructescence protects the fruits from heat up to 200°C for 2 min and this is similar to protection afforded by woody cones in other serotinous species. C. capitatum requires either heat or smoke to cue germination, whereas C. petiolare requires no cue, as is found in most other serotinous species. A combination of morphological modification associated with allometry of the whole plant body and physiological changes to germination requirements shows that a series of complex changes may be needed to develop serotiny from non-serotinous antecedents.

Additional keywords: fire, inflorescence–infructescence structure, Proteaceae, seed protection, seed storage.


References

Barker WR, Barker RM, Haegi L (1999) Introduction to Hakea. In ‘Flora of Australia. 17B’. pp. 1–30. (CSIRO Publishing: Melbourne)

Barker NP, Vanderpoorten A, Morton CM, Rourke JP (2004) Phylogeny, biogeography, and the evolution of life-history traits in Leucadendron (Proteaceae). Molecular Phylogenetics and Evolution 33, 845–860.
Phylogeny, biogeography, and the evolution of life-history traits in Leucadendron (Proteaceae).Crossref | GoogleScholarGoogle Scholar | 15522808PubMed |

Bell DT, Plummer JA, Taylor SK (1993) Seed germination ecology in southwestern Australia. Botanical Review 59, 24–73.
Seed germination ecology in southwestern Australia.Crossref | GoogleScholarGoogle Scholar |

Bellairs SM, Bell DT (1990) Temperature effects on the seed germination of ten kwongan species from Eneabba, Western Australia. Australian Journal of Botany 38, 451–458.
Temperature effects on the seed germination of ten kwongan species from Eneabba, Western Australia.Crossref | GoogleScholarGoogle Scholar |

Bennett EM (1995) Conospermum. In ‘Flora of Australia. 16’. pp. 224–270. (CSIRO Publishing: Melbourne)

Bond WJ (1985) Canopy-stored seeds reserves (serotiny) in Cape Proteaceae. South African Journal of Botany 51, 181–186.

Bradshaw SD, Dixon KW, Hopper SD, Lambers H, Turner SR (2011) Little evidence for fire-adapted plant traits in Mediterranean climate regions. Trends in Plant Science 16, 69–76.
Little evidence for fire-adapted plant traits in Mediterranean climate regions.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXhvFKit78%3D&md5=96c0607ba72a04a4c027b2d2d260de8cCAS | 21095155PubMed |

Bradstock RA, Gill AM, Hastings SM, Moore PHR (1994) Survival of serotinous seedbanks during bushfires, comparative studies of Hakea species from southeastern Australia. Australian Journal of Ecology 19, 276–282.
Survival of serotinous seedbanks during bushfires, comparative studies of Hakea species from southeastern Australia.Crossref | GoogleScholarGoogle Scholar |

Byrne M, Yeates DK, Joseph L, Kearney M, Bowler J, Williams MAJ, Cooper S, Donnellan SC, Keogh JS, Leys R, Melville J, Murphy DJ, Porch N, Wyrwoll K-H (2008) Birth of a biome, insights into the assembly and maintenance of the Australian arid zone biota. Molecular Ecology 17, 4398–4417.
Birth of a biome, insights into the assembly and maintenance of the Australian arid zone biota.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DC%2BD1cjhvFGruw%3D%3D&md5=18e1e5ae25a7438fbd76312775e9fb69CAS | 18761619PubMed |

Carpenter RJ, McLoughlin S, Hill RS, McNamara KJ, Jordan GJ (2014) Early evidence of xeromorphy in angiosperms: stomatal encryption in a new Eocene species of Banksia (Proteaceae) from Western Australia. American Journal of Botany 101, 1486–1497.
Early evidence of xeromorphy in angiosperms: stomatal encryption in a new Eocene species of Banksia (Proteaceae) from Western Australia.Crossref | GoogleScholarGoogle Scholar | 25253709PubMed |

Cowling RM, Lamont BB (1985) Seed release in Banksia: the role of the wet–dry cycle. Australian Journal of Ecology 10, 169–171.
Seed release in Banksia: the role of the wet–dry cycle.Crossref | GoogleScholarGoogle Scholar |

Crisp MD, Burrows GE, Cook LG, Thornhill AH, Bowman MDJS (2011) Flammable biomes dominated by eucalypts originated at the Cretaceous–Palaeogene boundary. Nature Communications 2, 193
Flammable biomes dominated by eucalypts originated at the Cretaceous–Palaeogene boundary.Crossref | GoogleScholarGoogle Scholar | 21326225PubMed |

Dixon KW, Roche S, Pate JS (1995) The promotive effect of smoke derived from burnt native vegetation on seed germination of Western Australian plants. Oecologia 101, 185–192.
The promotive effect of smoke derived from burnt native vegetation on seed germination of Western Australian plants.Crossref | GoogleScholarGoogle Scholar |

Enright NJ, Lamont BB (1989) Fire temperatures and follicle-opening requirements in 10 Banksia species. Australian Journal of Ecology 14, 107–113.
Fire temperatures and follicle-opening requirements in 10 Banksia species.Crossref | GoogleScholarGoogle Scholar |

Enright NJ, Keith DA, Clarke MF, Miller BP (2012) Fire regimes in Australian sclerophyllous shrubby ecosystems, heathland, heathy woodlands and mallee woodlands. In ‘Flammable Australia. Fire regimes, biodiversity and ecosystems in a changing world’. (Eds RA Bradstock, AM Gill, RJ Williams) pp. 215–234. (CSIRO Publishing: Melbourne)

Garside S, Lockyer S (1930) Seed dispersal from the hygroscopic fruits of Mesembryanthemum Carpanthea (Mesembryanthemum) pomeridiana N.E.Br. Annals of Botany 44, 639–655.

George AS (1998) Banksia. In ‘Flora of Australia. 17B’. pp. 175–250. (CSIRO Publishing: Melbourne)

Gill AM, Catling PC (2002) Fire regimes and biodiversity of forested landscapes of southern Australia. In ‘Flammable Australia. The fire regimes and biodiversity of a continent’ . (Eds R Bradstock, J Williams, MA Gill). pp. 351–372. (Cambridge University Press: Cambridge, UK)

Günster A (1994) Variability in life history parameters of four serotinous plants in the Namib Desert. Vegetatio 114, 149–160.

Hanley ME, Lamont BB (2000) Heat pretreatment and the germination of soil-and canopy-stored seeds of south-western Australian species. Acta Oecologica 21, 315–321.
Heat pretreatment and the germination of soil-and canopy-stored seeds of south-western Australian species.Crossref | GoogleScholarGoogle Scholar |

He T, Lamont BB, Downes KS (2011) Banksia born to burn. New Phytologist 191, 184–196.
Banksia born to burn.Crossref | GoogleScholarGoogle Scholar | 21388378PubMed |

He T, Pausas JG, Belcher CM, Schwilk DW, Lamont BB (2012) Fire-adapted traits of Pinus arose in the fiery Cretaceaous. New Phytologist 194, 751–759.
Fire-adapted traits of Pinus arose in the fiery Cretaceaous.Crossref | GoogleScholarGoogle Scholar | 22348443PubMed |

Keeley JE, Bond WJ (1997) Convergent seed germination in South African fynbos and Californian chaparral. Plant Ecology 133, 153–167.
Convergent seed germination in South African fynbos and Californian chaparral.Crossref | GoogleScholarGoogle Scholar |

Keeley JE, Pausas JG, Rundell PW, Bond WJ, Bradstock RA (2011) Fire as an evolutionary pressure shaping plant traits. Trends in Plant Science 16, 406–411.
Fire as an evolutionary pressure shaping plant traits.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXpvFWqsr4%3D&md5=7324353006264cbcc55eae0443295af3CAS | 21571573PubMed |

Ladd PG, Midgley JJ, Nield AP (2013) Serotiny in southern hemisphere conifers. Australian Journal of Botany 61, 486–496.
Serotiny in southern hemisphere conifers.Crossref | GoogleScholarGoogle Scholar |

Lamont BB (1991) Canopy seed storage and release – what’s in a name? Oikos 60, 266–268.
Canopy seed storage and release – what’s in a name?Crossref | GoogleScholarGoogle Scholar |

Lamont BB, Barker MJ (1988) Seed bank dynamics of a serotinous, fire sensitive Banksia species. Australian Journal of Botany 36, 193–204.
Seed bank dynamics of a serotinous, fire sensitive Banksia species.Crossref | GoogleScholarGoogle Scholar |

Lamont BB, Cowling RC (1984) Flammable infructescences in Banksia: a fruit-opening mechanism. Australian Journal of Ecology 9, 295–296.
Flammable infructescences in Banksia: a fruit-opening mechanism.Crossref | GoogleScholarGoogle Scholar |

Lamont BB, Enright NJ (2000) Adaptive advantages of aerial seed banks. Plant Species Biology 15, 157–166.
Adaptive advantages of aerial seed banks.Crossref | GoogleScholarGoogle Scholar |

Lamont BB, He T (2012) Fire-adapted gondwanan angiosperm floras evolved in the Cretaceous. BMC Evolutionary Biology 12, 223
Fire-adapted gondwanan angiosperm floras evolved in the Cretaceous.Crossref | GoogleScholarGoogle Scholar | 23171161PubMed |

Lamont BB, Le Maitre DC, Cowling RM, Enright NJ (1991) Canopy seed storage in woody plants. Botanical Review 57, 277–317.
Canopy seed storage in woody plants.Crossref | GoogleScholarGoogle Scholar |

Le Maitre DC (1984) Current interpretations of the term serotiny. South African Journal of Science 81, 284–290.

Mast AR, Milton EF, Jones EH, Barker RM, Barker WR, Weston PH (2012) Time calibrated phylogeny of the woody Australian genus Hakea (Proteaceae) supports multiple origins of insect-pollination among bird-pollinated ancestors. American Journal of Botany 99, 472–487.
Time calibrated phylogeny of the woody Australian genus Hakea (Proteaceae) supports multiple origins of insect-pollination among bird-pollinated ancestors.Crossref | GoogleScholarGoogle Scholar | 22378833PubMed |

Matusick G, Ruthrof KX, Brouwers NC, Dell B, Hardy GS (2013) Sudden forest canopy collapse corresponding with extreme drought and heat in a Mediterranean-type eucalypt forest in southwestern Australia. European Journal of Forest Research 132, 497–510.
Sudden forest canopy collapse corresponding with extreme drought and heat in a Mediterranean-type eucalypt forest in southwestern Australia.Crossref | GoogleScholarGoogle Scholar |

Milich KL, Stuart JD, Varner JM, Merriam KE (2012) Seed viability and fire-related temperature treatments in serotinous Californian native Hesperocyparis species. Fire Ecology 8, 107–124.
Seed viability and fire-related temperature treatments in serotinous Californian native Hesperocyparis species.Crossref | GoogleScholarGoogle Scholar |

Moreira B, Tormo J, Estrelles E, Pausus JG (2010) Disentangling the role of heat and smoke as germination cues in Mediterranean Basin flora. Annals of Botany 105, 627–635.
Disentangling the role of heat and smoke as germination cues in Mediterranean Basin flora.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DC%2BC3c3ksFSjsQ%3D%3D&md5=d586d4b0c491134dbb91015adaef5ebeCAS | 20181568PubMed |

Parolin P (2001) Seed expulsion in fruits of Mesembryanthema (Aizoaceae): a mechanistic approach to study the effect of fruit morphological structures on seed dispersal. Flora 196, 313–322.

Paull R, Hill RS (2010) Early Oligocene Callitris and Fitzroya (Cupressaceae) from Tasmania. American Journal of Botany 97, 809–820.
Early Oligocene Callitris and Fitzroya (Cupressaceae) from Tasmania.Crossref | GoogleScholarGoogle Scholar | 21622446PubMed |

Roche S, Dixon KW, Pate JS (1997) Seed aging and smoke, partner cues in the amelioration of seed dormancy in selected Australian native species. Australian Journal of Botany 45, 783–815.
Seed aging and smoke, partner cues in the amelioration of seed dormancy in selected Australian native species.Crossref | GoogleScholarGoogle Scholar |

Rodríguez-Ortega C, Franco M, Mandujano MC (2006) Serotiny and seed germination in three threatened species of Mammillaria (Cactaceae). Basic and Applied Ecology 7, 533–544.
Serotiny and seed germination in three threatened species of Mammillaria (Cactaceae).Crossref | GoogleScholarGoogle Scholar |

Santini BA, Martorell C (2013) Does retained-seed priming drive the evolution of serotiny in drylands? An assessment using the cactus Mammillaria hernandezii. American Journal of Botany 100, 365–373.
Does retained-seed priming drive the evolution of serotiny in drylands? An assessment using the cactus Mammillaria hernandezii.Crossref | GoogleScholarGoogle Scholar | 23345416PubMed |

Sauquet H, Weston PH, Anderson CL, Barker NP, Cantrill DJ, Mast AR, Savolainen V (2009) Contrasting patterns of hyperdiversification in Mediterranean hotspots. Proceedings of the National Academy of Sciences, USA 106, 221–225.
Contrasting patterns of hyperdiversification in Mediterranean hotspots.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXltF2ksw%3D%3D&md5=256c19593b46a537732560d0fb664a3aCAS |

Schumann D, Kirsten G (1992) ‘Ericas of southern Africa.’ (Fernwood Press: Vlaberg, South Africa)

Stackey K (1987) The aftermath of the Ash Wednesday wildfires. Some observations of the behaviour of cultivated native plants. Journal of the Society for Growing Australian Plants 10, 178–181.

Tieu A, Dixon KW, Meney KA, Sivasithamparam K (2001) The interaction of heat and smoke in the release of dormancy in seven species from southwestern Western Australia. Annals of Botany 88, 259–265.
The interaction of heat and smoke in the release of dormancy in seven species from southwestern Western Australia.Crossref | GoogleScholarGoogle Scholar |

Vigilante T, Dixon K, Sieler I, Roche S, Tieu A (1998) ‘Smoke germination of Australian plants.’ RIRDC Publication No 98/108. (RIRDC)

Whelan RJ, Brown CL (1998) The role of Callistemon fruits and infructescences in protecting seeds from the heat of fires. Australian Journal of Botany 46, 235–239.
The role of Callistemon fruits and infructescences in protecting seeds from the heat of fires.Crossref | GoogleScholarGoogle Scholar |