Know thine species

The show dahlia

The show dahlia

You can quite easily live out your gardening days without ever worrying about species and hybrids. Indeed you can, but as with most activities, many people will find that the more they know, the more they enjoy what they are doing.

At its simplest level, species are the natural form of a plant in the wild. And all plants originated somewhere in the wild.

Hybrids are mix of two different species in the first instance and after that they can quickly become a mix of many different species and resulting hybrids getting ever more complex genetic makeup. There is no value judgement in the rights and wrongs of that. Sometimes these hybrids occur in the wild without any human intervention (usually referred to as “natural hybrids”). Often it is done deliberately to try and improve plants.

A variation on controlled hybridising is line breeding – raising many seed from a plant and selecting only the very best with which to continue. Then seed from those best plants is raised time after time until it shows stability. Seed can be extremely variable and this form of line breeding is trying to edit out the less desirable aspects over several generations.

It happens all the time with edible crops. Think how much sweet corn and kiwifruit have changed over the years. The original, wild collected species of edible crops are often poor shadows of what we have now in terms of yield, reliable production, ease of handling and palatability.

It is not always true, of course. Sometimes commercial imperatives have seen us saddled with inferior tasting product – tomatoes are a prime example. And there are concerns about the loss of the wild species which are important to maintain the gene pool for food crops.

As far as ornamental plants are concerned, most of us will have gardens which are a mix of species and hybrids. There are no hard and fast rules although I have met a fair number of gardeners in my time who parade a collection of species only as a badge of status.

Species Camellia gauchowensis

Species Camellia gauchowensis

Some species have a simple charm which is lost in their showier hybrids. Others are nondescript in the extreme. Some highly desirable species are simply damn difficult to grow whereas the hybrids bring new vigour which makes them much more rewarding garden plants. Sometimes there are species which make splendid garden plants but they can be overlooked because their names are not appealing. Camellia gauchowensis has been the standout star of that family here recently and why anybody would grow the likes of Mine No Yuki instead of C. gauchowensis, I don’t know.

We have been revisiting the camellia species as we pick over the best options in the face of the devastating camellia petal blight which has so affected many of the hybrids we grow. It is not that the species don’t get it. It is just that some of them have less susceptibility and have other good characteristics which are worth looking at. More on this in the future.

Show blooms, no matter which plant family, often tend to be over-bred hybrids which are but distantly related to original species. Dahlias which are too heavy to hold their heads up without staking, bizarre daffodil forms, overblown cyclamen or chrysanthemums, enormous begonia flowers – anything that is bigger, allegedly better or a novelty genetic freak.

Named hybrid aster at top, self sown seedling at bottom

Named hybrid aster at top, self sown seedling at bottom

But controlled hybridising can also give us garden plants which are hugely better performers. You can see in the photograph of asters that the abundance of blooms at the top are from a named hybrid whereas the few poor specimens at the bottom are from a self sown seedling which has probably reverted closer to how the original species looks.

Hybrid arisaemas for our own garden

Hybrid arisaemas for our own garden

I am of course married to a plant breeder who is driven by the desire to create better performing garden plants. Sometimes it is just to get plants which will grow better in our garden here. His work with arisaemas is of this ilk. Many of the desirable arisaemas are a battle to grow in our conditions with insufficient chill and they simply don’t come back a second year. By hybridising two different species, he can get hybrid vigour which means they are much more reliable and stronger growing.

Other plants may be hybridised to look for new or improved characteristics – extending the colour range, reducing the impact of disease, getting more compact growth, better floral display, a longer season, sterility (to avoid unwanted seeding) or bringing the best features of different hybrids together in one plant. There are many reasons to hybridise and one of the final tests before selecting a new cultivar for release is to measure it against both the originating species and the actual parent plants. If it is not a significant improvement, then it won’t get released on the market.

Hybrids have their place in the ornamental garden and in the edible garden. But in a world which is squeezing the natural environment in every way possible, we need to retain the original species for reasons of ecology and bio-diversity. The more people who understand the difference the better – even more so if they can move away from the modern “green” cliché that says the original species are, by definition, better. They are not, but they are important.

First published in the Waikato Times and reprinted here with their permission.

1 thought on “Know thine species

  1. James Golden

    Yes. So many native plant enthusiasts think: “Hybrid, bad,” “Species, good.” We DO need both. Some hybrids are frivolous monstrosities. Others make it possible to feed the world.

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