Tag Archives: plant species

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.

What is in a name? Quite a bit, sometimes.

I will take Rhododendron nuttallii any time

I will take Rhododendron nuttallii any time

I was looking at a newly released NZ gardening book and happened upon praise for a fruit described as a Chilean guava. For decades, the term Chilean guava, sometimes strawberry guava, has been widely known in this country to refer to a South American fruit called Psidium littorale. It is a biggish, evergreen shrub which produces fruit about the size of a large marble or a gobstopper in red or yellow with rather large pips. It is at least the same genus as the tropical guava – the pink fruit that most of us know in tins from South Africa.

Enter Myrtus ugni (or Ugni molinae to be more correct), usually called the New Zealand cranberry (to which it is entirely unrelated). In Australia, it is known as the Tazzieberry but internationally it is often referred to as the Chilean guava. In recent times there has been a growing tendency in the nursery and retail trade (and now in publishing) to adopt the international common name and to refer to the New Zealand cranberry (aka Myrtus ugni) as the Chilean guava. No matter that there is a pre-exisiting fruiting bush widely known as that. In the aforementioned book, the only reason I knew the author was writing about Myrtus ugni and not Psidium littorale was by the picture. That is because the header was: “Chilean guava” with no botanical name given at all. Sometimes writers and publishers can dumb stuff down so far that they almost guarantee failure.

Two entirely different plants, both commonly called the Chilean guava

Two entirely different plants, both commonly called the Chilean guava

Common names can be helpful in gardening where proper names are often in Latin and hard to remember, but they are only helpful when there is shared understanding about the plant being so labelled. There is no excuse for not putting the proper name in smaller type beneath the common name in books, or indeed for failing to give alternative common names that are in wide usage.

What novice gardeners need is not the complete dumbing down of information to a jazzy but relatively useless level. They need skilled interpretation so that the wealth of information is sorted for them and they are gently encouraged to lift both their knowledge and skills level. Part of that is learning about plant names and plant families.
Why does it matter whether you understand these things? Think of cooking. You can make a perfectly acceptable cheese sauce using any old cheddar but to lift your cooking to a higher level, it is usually necessary to understand the different types of cheeses and just when Parmesan is going to give a better result than Mozzarella or even Pecorino.

You can enjoy your garden and fill it with seeds and cuttings without knowing the names of any of them, let alone where they come from or to which plant family they belong. You may even be perfectly happy growing one Chilean guava while thinking it is the other Chilean guava you have. But it becomes a great deal more interesting when you know more. And the more you know, the more likely your outcomes will be successful and the better your garden will be.

It was an eighteenth century Swedish botanist, Carl Linnaeus, who reorganized the structure of living things, including plants, into the order or sequence (called taxonomy) that we still adhere to today. You can get by quite satisfactorily just understanding the end points of species and genus.

The species is specific to one plant, though there can be some variation within a species – think of brothers and sisters. So if you take the gorgeous Rhododendron nuttallii (and it is so gorgeous, I will take it any time), the nuttallii is the species. There are differences between various forms of nuttalliis but botanically they all very close. The rhododendron part of the name is the genera and there are many different species within that genera – in fact all the different rhododendron, vireya and azalea species. They are like the cousins, second cousins and third cousins plus assorted relatives.

Plant names are in two parts: first the genus and then the species. Hence Rhododendron nuttallii. Even the humble common garden bean has a two part name – Phaesolus vulgaris for most green beans and Phaesolus coccineus for runner beans. Runner beans are a different species to green beans but take it a step up and they are the same genus. The naming of plants in this form is one of Linnaeus’ most enduring legacies. Prior to that, the naming of plants was entirely random and told you nothing at all about the botany of the plant (which is a bit of a problem when it involves medicinal herbs). It was also a source of considerable confusion and duplication.

Linnaeus’s system of classifying plant species through names (called binomial – two names) has stood the test of time over nearly 300 years. But apparently in this country, it is too difficult for us to grasp. If the trends of the past decade are anything to go by, we must return to the pre-Linnaeus era because we are only capable of managing common names, no matter that it can cause confusion. It is apparently asking too much that the botanical name be run alongside the common name.

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