The root market

Walk the heath and every plant you see is half a plant. The other half is underground, and it is not a root. Almost every plant on this coast runs its roots in partnership with fungi: threads finer than any root, reaching further than any root could afford, trading the minerals they find for the sugar the plant makes in the light. Ecologists call the arrangement mycorrhiza. We call it the root market, because that is how it behaves: a trading floor under the sand, where sugar buys phosphorus and nitrogen, and nothing is handed out free.

How do we know the market is real here, and not a fine idea imported from richer ground? One local measurement. The scribbly gum has been grown alongside a cousin from fat country, on rich soil and on wallum sand, and the result cut clean: on rich soil neither tree leaned much on its fungal partners, and on wallum sand both leaned on them heavily. The market is not a fixed habit of the tree. It is what the poverty of the ground calls into being, and no ground on this coast calls louder than the wallum’s.

Now the honest part. That single trade, the scribbly gum’s, is the only one in wallum sand anyone has measured. Nobody has yet put a name to a single wallum fungus doing the trading; the partners in this market are, in our record so far, anonymous. And not every plant is a customer. The banksias, the very emblem of this country, mostly sit the market out and mine their phosphorus themselves, with chemistry of their own. So picture the market as this page must honestly draw it: one stall lit, the scribbly gum’s, and behind it a whole trading floor working in the dark. Whoever first names the fungi under this heath will write a page we cannot yet write.