Seed dispersal and germinationSeed dispersal and germination

Seed dispersal and germination

Seeds of Wollemi Pine are relatively light compared to other gymnosperms (ranging from 10–44 mg; Meagher & Offord unpubl. data) and winged and are dispersed short distances within existing stands by gravity and wind. Aerial dispersal appears to be in a downslope direction as seedlings occur up to 30 metres downslope of the nearest tree but are more limited upslope, likely because of the high cliffs subtending most stands. It is possible that there may be very rare longer-distance movement of seeds by birds if they feed on cones and move the cones to another feeding tree. This could account for the current distribution of Wollemi Pine. There may also be movement of seeds downstream by water if floods coincide with seed fall (Offord et al. 1996). It appears likely that a proportion of seed is lost to predation. Crimson Rosellas (Platycercus elegans) have been observed foraging Wollemi Pine cones; a rat (Rattus rattus) skull has been found in one of the wild Wollemi Pine stands, indicating their presence (and potential to act as seed predators); and insect damage to seeds has also been observed (Offord et al. 1999).

For the first 20 years after the species’ discovery, the only source of cones and seeds for seed banking, propagation and research was the wild population. This has changed in recent years, as Wollemi Pines in cultivation have begun to mature and provide alternative sources of seed.

Laboratory trials suggest that seeds of Wollemi Pine germinate in the temperature range 24–30°C. However, the rate of germination is somewhat protracted unless the seeds are subjected to a period of cold moist stratification, at < 10°C, followed by incubation in the optimal range. This period of stratification is analogous to the temperature regime experienced after autumn seed fall, with seeds that survive winter germinating quickly in spring and early summer, presumably to take advantage of the moister conditions (Offord and Meagher 2001). In the field, seed emergence phenology is bimodal, with peaks in autumn and spring.

Seeds are orthodox or intermediate with regard to their storage capability; they can be dried down to less than 10% moisture content and stored at low temperature (-18°C) for up to five years, and possibly longer (C. Offord, pers. comm.). Wollemi Pine seeds contain around 40% oil, including a short chain omega-3 fatty acid not commonly found in plants. Seeds stored at sub-optimal temperatures (> 0°C) show decreased germinability and viability, which correlates with an increase in lipid degradation (Ng et al. 2024).