Indigenous Landscape Design Australia

What you need to know about hybrid plants

A hybrid plant is the result of interbreeding related species, usually of the same genus.

Hybrids occur in nature when the distribution of two related species coincides or overlaps. For example, Grevillea acanthifolia and Grevillea laurifolia, both endemic to (restricted to) the Blue Mountains west of Sydney, New South Wales, interbreed to form Grevillea x gaudichaudi (Grevillea acanthifolia x Grevillea laurifolia), a natural hybrid that combines features of both species.

Hybrids are also produced artificially. Many production nurseries breed genetically different species to concoct new hybrids  – regardless of their natural distribution – for characteristics such as enlarged or double flowers, bizarre or intensified colours, and/or extended flowering.

Increased vigour is another characteristic of hybridisation. Yet the resultant hybrids are often structurally unstable and vulnerable to mechanical stresses or dependent on increased water and nutrients.

Although hybridisation occurs in nature, "problems arise when it's human-caused", says Nina Fascione, vice president of species conservation for the Defenders of Wildlife, USA.

"Some of these hybrids are sterile, but that doesn't mean they don't cause other problems", says conservation geneticist at the University of Maine, Judith Rhymer. "It's still a conservation issue because parents are contributing less and less to the next generation."

And that’s the crux of the problem. Humans are bringing together plants and animals that have never seen each other before, through habitat destruction and the international nursery and pet trades.

The selective breeding of hybrid plants with enlarged or double flowers reduces or obliterates the stamen, the protein-rich, pollen-producing part of the flower. This process renders the plant sterile and of little or no food value to honeyeaters (nectar-feeding birds). If nectar is present, pollinating insects may be unable to reach it, rendering the plant of little or no value to pollinating insects and insectivorous birds.

Hybrid native plants with oversize flowers and extended flowering seasons, grevilleas in particular, attract aggressive, territorial nectar feeders such as the Wattlebird and Noisy Miner that are neither vulnerable nor endangered and that drive out small songbirds such as the vulnerable Painted Honeyeater and Pied Honeyeater, and the endangered Regent Honeyeater, and many others that now face serious decline or extinction.

In her 1958 classic Garden Design, the late, great landscape architect Sylvia Crowe (1901 - 1997), raises a related issue:

"One of the more subtle qualities of plants is a certain relationship in colour and proportion between the stem, the leaves and the flowers, and the poise of the flowers upon their stems. It is these qualities which give the plant species a grace often lacking in the garden hybrids . . .  The intensifying of flower colours by hybridisation can also throw out the subtle harmony of the wild plant."

In his posthumously published La Botanique, Jean-Jacques Rousseau (1712 - 1778), reaches much the same conclusion. He dismisses hybrid plants with enlarged or double flowers, as "nature disfigured by man. Waste no time examining them", he insists. "Nature is no longer there; she refuses to be reproduced by such deformed monsters."

Rousseau wasn’t entirely correct: Some nursery-bred hybrids between species from separate ecosystems, do produce pollen, and these pose a further threat to the environment: Birds that feed on them may pollinate local native species, thus polluting the local gene pool. For example, CSIRO scientists have discovered that pollen from fertile, nursery-bred hybrid grevilleas in gardens adjacent to Wee Jasper New South Wales bushland, has contaminated the rare Grevillea iaspicula.

So why, despite the drawbacks, does the nursery industry continue to breed and promote these “deformed monsters”?  The short answer is increased profits, as the nursery industry follows the manufacturing industry’s necessarily competitive ‘economies of scale’ and ‘export or die’ business model.

Plant Breeders Rights (PBR) are exclusive commercial rights, like patents and copyright, and are administered under the Plant Breeder's Rights Act 1994. Plant breeders have exclusive rights to produce or reproduce the plant, offer it for sale and export it. By promoting these plants through media exposure and eye-catching labels, nurseries that breed and/or sell them, gain competitive advantage (albeit to the detriment of wildlife and the environment).  

A cooperative business model supported by continuing public education and a cooperative marketing campaign, is long overdue. This needs to include a sustainable, eco-aware, Australia-wide network of nurseries offering an informed selection of the most desirable local and regional species, suited to garden cultivation.

Consider the lilies of the field, how they grow; they toil not, neither do they spin. Yet I say unto you, King Solomon in all his glory was not arrayed like one of these.
Jesus of Nazareth: The Gospel of St Luke

Strong words indeed, as Solomon was renowned for the splendour and beauty of his apparel. Yet Jesus claims it falls far short of the lilies of the field – the wildflowers.

Which raises the question: Are we looking for beauty in the wrong places? And in the process, are we missing the natural beauty of the wildflowers at our feet?

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