Plants from elsewhere

"Without hard work, nothing grows but weeds” said the US religious leader and author, Gordon B. Hinckley, in 1994.

The wisdom proffered in this tired old saw is predicated on at least two dubious propositions: that weeds are not desirable, and that hard work is. I’ll leave the work ethic question to spiritual guides and philosophers, but I’m happy to tackle the weed matter. 

In Australia, weeds are demonised by farmers, environmentalists and a certain kind of gardener. There are good reasons for this stance – as I’ll get to later in the chapter – but my starting point is that a weed has no intrinsic ethical merit or demerit.

In The Bush: Travels in the Heart of Australia, Australian author Don Watson considers our tolerance of native Australian, exotic and local indigenous plants in gardens, and more broadly, in extra-garden settings (‘the bush’). He laments the damage and displacement of native species by rampaging weeds but also the futility of returning land to some imagined original state or trying to create a garden with no impact on the broader environment. And there’s the rub.

The most compelling reason for floral exclusivity is to avoid adding to Australia’s ‘weed problem’. That problem is a big one, with scientists at the CSIRO estimating a cost to Australia of over $4 billion a year in control and lost production. Humans have transported some 28 000 plants species to Australia, about the same number as the native species that grew here before European and First Australian arrivals. Most of the introductions were deliberate, and more than 2500 now grow and spread in Australia without our further assistance.

Gardening is – at its most fundamental – the introduction and encouragement of plants we like and the discouragement of those we don’t. Encouragement amounts to watering, fertilising, formative pruning and the like. Discouragement usually involves removing offending plants to the point of annihilation of that species within areas under our control. We parse animals in the same way, favouring pollinators and destroying plant predators.

With plants, it’s all about selection: choosing those we want to be part of our collection or landscape and rejecting the rest – particularly weeds or poorly performing specimens. While there may be ambiguity around what to do with an attractive, adventitious plant, perhaps arriving by seed, or a weedy plant that just happens to create a useful ground cover, it’s generally easy to categorise plants as good and evil within the context of a garden.

On the other side of the fence, and more pertinently beyond the city limits, the morality of plant selection can be vexed. After reading The New Wild: Why Invasive Species will be Nature’s Salvation by Fred Pearce, I am primed to accept all plants as worthy participants in ‘nature’. Yet while I understand Pearce’s philosophical and practical conclusion, I still get protective about a rare orchid growing in the clapped-out bush near Castlemaine, or a remarkable seaweed attached to a rocky platform just off the coast. I’m not quite post-modern enough to accept every plant as the same. That said, and as you’ll read in this chapter, I’m a lot more liberal than many of my colleagues and friends.

Let me finish with something you won’t find in most gardens, except as an extract or in dried form – a seaweed. Its very name suggests this might be sometime unwanted and detrimental to the environment. Yet these marine algae – as we know them slightly more formally – are an essential part of coastal ecosystems.

I happen to have a one named after me, Entwisleia bella, an extremely rare seaweed, confined to an area the size of a standard living room off the coast of Hobart. I’ll return to it later in the book but like most gum trees, many terrestrial orchids and half a dozen kangaroo species, this alga is a unique part of Australia’s native biota. It is also seasonal and even at its peak there are no more than a dozen of the red feathery algae attached by a small adhesive clamp to subtidal rocks.

It is rarer and, as it turns out, evolutionarily more distinct (that is, it has fewer living close relatives) than the Wollemi pine. Personally, I would be very unhappy to hear that the last individuals of Entwisleia bella on Earth were eaten by an invasive shellfish or shaded by an aggressive algal weed from elsewhere. I also understand that very few people will ever see this seaweed in situ and may not appreciate its beauty or significance the way I do.

That doesn’t mean we should knowingly destroy Entwisleia, although I accept its conservation may have to be ‘prioritised’ against other imperatives. I accept also, that an ‘anything goes’ attitude to weeds and pests might lead to the extinction of a species such as this. In a similar way, farming seaweeds for fuel or other products needs to be approached with great caution so we don’t repeat the devastation caused by much agriculture on land. 

You may not share my concern about this seaweed, but when the Wollemi pine, the crimson spider-orchid, or Gilbert’s potaroo are under threat from invasive weeds our sympathies are seldom with the interloper. There are good scientific, philosophical, empathetic, maybe even spiritual reasons, why we should care. The question is, how much?

*    *    *

The third teaser from my new book of 50 essays, The Sceptical Botanist: Separating Fact from Fiction (CSIRO Publishing, 2025), available from 1 August 2025 at CSIRO Publishing and all good bookstores. 

This is my introduction to the second chapter, about weeds and the way we respond to them. The illustration is from the last essay in this chapter, 'What if weeds?', a contemplative piece on alternative histories for the arrival of exotic plants into Australia.

Jerome Entwisle provided the cartoon for this essay, here and in the book.