Plant Profile- Bunya and Beyond

A big influence on me was reading Mark Shepard’s “Restoration Agriculture”. In this book he outlines how he moved to a region that was traditionally too cold for chestnuts and proceeded to rapidly select genetics that performed under conditions with virtually no artificial inputs (STUN method, standing for strategic total utter neglect). When I contacted him about going down a similar path, with dreams of subtropical chestnuts, his advice was to focus on the local species I wished to foster and start from there. Before this time I had thought about working with bunya nuts (Araucaria bidwillii) but hesitated. These large coniferous trees trace their ancestry back to the age of the dinosaurs but were now restricted to a fairly small region around my farm. I suspected they didn’t have much genetic diversity left to work with, and on top of that they were fairly slow growing. The nuts are impressive however, ranging from 4-8 cm long and packed with a rich and starchy kernel that is no harder than a chestnut to extract and use. I tried eating some locally grown nuts I scavenged and my reluctance diminished with each bite. The trees produce a moderate crop most years but now and then produce a much larger harvest. As one of these masting years rolled around I decided to get out into the field and assess their diversity more closely.

Two full days later of driving along remote mountain roads, scrambling down sheer hills covered in prickly lantana and stinging trees I got my answer. The remaining old remnant trees were far more diverse than I anticipated. It seems most of the recently planted trees are sourced from much narrower genetics, perhaps related to a push to try the species for forestry in the 1970s. The old remnant trees varied in tree form, cone shape and size, and nut shape and size as well. A couple of trees appeared to be precocious with considerable crops at approximately 7-10 years old by my reckoning. Bunyas normally take about 15 years to mature, a major factor that turns people off planting them. It turned me off trying to breed them since it meant I could only squeeze in one or two generations before my time on the planet was up (I am in my early 40s now). Most alarmingly I observed that the remnant trees had undergone close to zero natural recruitment of seedlings in the last few decades, with all observed trees well over 70 years of age. The cones were quickly torn apart by rodents and I suspect introduced rats now devour the nuts where the original native species may have buried them for later, fostering germination. As such this means the species is functionally extinct in the wild and with trees only lasting so long the clock is ticking on preserving this diversity.

As a result I decided to take on bunya nut as a serious breeding project.  Who else would have the access to the wild trees, sufficient land to grow a reasonable sized population, with sufficient stability to see the project through coupled to sufficient remaining lifespan to see the project reach a result that can be shared more widely? Having the interest and knowledge to pull something like this off, and be crazy enough to try…..those aren’t found in normal folk either. I felt a bit like the first lunatic who decided climbing on the back of a horse was a good idea.

Since starting the project I have figured out some guidelines for propagation. The trees are incredibly hardy but have a few key requirements. The seeds are viable only for a short period and must be sowed without delay. Like other starchy nuts they have a high oxygen consumption rate and won’t tolerate being smothered with soil. Nuts can be buried just below the surface in common potting soil and watered sparsely, or alternatively can be sowed on the surface under a few layers of hessian that is kept fairly damp. The second approach has the advantage of letting you peel back the hessian and monitor progress, picking out blank nuts before they rot, which is useful when sowing large numbers of seed densely in group pots. Seed must be protected from vermin, who will go to extraordinary lengths to find them. The seed germinate by putting down a root that thickens into a small tuber. The seed then rots or dries off, leaving the geotuber to sit dormant for a variable amount of time. Some send up a shoot almost immediately while others wait for up to a year. I sow in group pots to make rat proofing easier then repot the dormant geotubers after 4-6 months into individual pots to grow out. My rats don’t seem interested in the geotubers. Once the trees reach about 20 cm tall they are ready to plant out during good weather. Even during dry times they establish well for me with a couple of dripper bottle waterings and a tree guard. After a couple of years they grow over 1 m tall. The goats don’t seem to damage the central growing point after this, so the bunya groves should return to grazing in time.

At the end of gathering this diversity I still wasn’t quite satisfied. My aim is not just to mothball existing genetics but to develop something new and so useful that people will plant it all across the planet. Most domestication events occur when two or more wild species hybridise. From this initial highly diverse hybrid population the individuals with the most appealing traits can be selected. The vast majority of significant domestic crop species come from ancient accidental hybridisation events, including wheat, chestnuts, apples, brassicas and potato. This process happened in living memory with another native species, the macadamia, which also originated just up the road from me. That one random cross gave rise to a multimillion dollar industry. Bunya has much more potential I believe.

I wondered if I could tap into the same process of domestication by hybridisation with bunya. With a bit of research it turned out there were many other species in the genus, but two in particular grabbed my attention. Araucaria angustifolia, known as the parana pine, grows in southern Brazil in a region with a very similar climate to my farm. The indigenous people eat the starchy nuts that are not as large as bunya but open easily after boiling. Araucaria araucana, known as the monkey puzzle tree, grows in Chile in a cooler climate than my farm but is known to grow in my area, and also has useful edible nuts. Both species appear to hybridise with bunya, with examples known from a few collections. Even better than this both South American species have separate male and female trees, unlike the mostly bisexual bunya. This means I can cull the males from these exotic species as they mature. The remaining females must then be pollinated by nearby bunya nuts, with the first seeds being produced hopefully from the most precocious bunyas. It also means the bunya nuts themselves will produce diverse but non-hybrid seed that can retain the best of the local diversity.

Through a lot of searching and scrimping my limited income I now have a healthy batch of both parana pines and monkey puzzle seedlings growing alongside my bunya seedlings. Once the monsoonal summer rains arrive they will all be planted out together in a 15 acre grove, closer together than ideal for mature trees to allow for about half of them to be culled as they mature. I opted to plant the bunya in one approximate contour row in semi-random order. Each block of ten or so trees I planted had at most one seedling of each collection locality within it, mixed up in random order. This was to ensure that each locality strain got placed in a diverse range of locations to sample our mixed up soils and aspects widely. It also meant that culling of the weaker trees was less likely to leave large gaps in the planting as might happen planting blocks of single varieties, or that trees from two localities generally worth keeping don’t end up crowded next to each other in each block, as might happen if I planted each block with the same order of varieties. They currently have locality labels on them that I will soon write into a hard copy file but fully expect the information will be lost as they mature. Labelling individual trees in a way that lasts for many decades is difficult and I am not convinced it is that important. Each tree must stand or fall on its own obvious merits and flaws, and knowing its surname won’t really change that. The parana and monkey puzzle will be planted in the next contour row up the hill, with a second row of bunyas above them. This should maximise wind pollination of the exotic species regardless of the wind direction.

There is an old Greek saying “Society grows great when old men plant trees whose shade they know they shall never sit in”. I am lucky enough that I will most likely live to see these trees reach maturity, and maybe even the first generation of their children. My vision stretches far beyond that, with great groves of bunya hybrids from Cairns to Melbourne and further across the globe, inhaling levels of carbon dioxide they haven’t enjoyed in millions of years, yielding staple carbohydrates plus grazing land for stock and providing the foundation for a society that has not yet put its shoot up into the light but instead sits waiting in the earth for the right moment to emerge.

Fresh bunya nuts ready for eating

Bunya seed germinating under hessian

Geotubers tipped out and ready for potting on. Take care not to break the new shoots.

Precious parana pine seedlings emerging.

Bunya seedlings transplanted out into tree guards with a dripper bottle.

Year old bunya seedlings ready for planting out.