Identifying plants
Identifying plants presents some of the same challenges faced when trying to identify invertebrates.
Firstly, there are thousands of species of flowering plants. Happily, however, most have been described and named scientifically (quite unlike the situation for invertebrates or for fungi!)
Secondly, as is the case with invertebrates, there is a special vocabulary used to describe plants and their parts. Learning this language goes along with learning plant anatomy – and both are essential skills to develop for botanical study.
And, finally, there is the challenge of individual variation. Depending upon the particular environment and growing conditions, individual plants of the same species can look radically different.
But there is plenty of good news too.
The basic 'plan' for all flowers is the same. In different families, this basic plan is variously modified but the fundamentals are constant.
There are excellent, comprehensive resources for plant identification down to the species level – both in text form and on-line.
And unlike many animals, plants don't bite and they aren’t camera shy!
There are two basic strategies for plant identification:
Use the CV tool in iNaturalist - this works surprisingly well for many plant species.
The systematic approach detailed below
Tip 1 – Become familiar with the parts of a flower
A quick web search will yield any number of useful images or even tutorials on floral structure. If you've studied biology this will already be familiar. But if you haven't, it is essential knowledge to have before you start trying to sort one plant family from another. It's simple and will take no time to master.
Tip 2 – Start by getting to know the floral characteristics of a few significant taxa
If you are new to plant identification, collect a few specimens and start by getting to know the parts of the flowers and what distinguishes the family or genus. Perhaps start with Leptospermum - the plants are easy to come by as the family is widely cultivated, the flowers are large enough to examine, and the fruit are always present on the stems. Solanaceae (which includes tomatoes, capsicum and chillies) is another family with a simple floral plan, showing all the floral parts in a regular array. A lily, even one from the garden, is a good way to become familiar with the 'monocots'. And a pea flower is a good introduction to the differences between bilateral symmetry and radial symmetry - a common modification of the floral 'bauplan'.
Having mastered the basics of flower structure, take the challenge of Eucalyptus, Acacia (wattle) and Grevillea, Banksia or Hakea (Proteaceae). Again, there are plenty of cheat-sheets available on line. And it's fun!
Observations and data
Typically, leaves alone are not enough to identify a species. We always take the opportunity to identify plants when they are flowering or fruiting. In most cases, flowers are needed for a positive identification.
Tall eucalypts pose a special problem in accessing the flower buds, flowers and fruit. Look for fallen branches but be alert to the possibility that these may have come from neighbouring trees of a different species.
If you are relying on photos, take lots! And of different parts of the plant – the whole plant, flowers, buds, leaves and stems – and at different levels of magnification. You can often get a photo of a plant that is adequate for identification purposes even with a mobile phone camera.
Size matters. When taking photos in the field, if we don't have a ruler on hand we try to include something in the photo to give us a scale. A coin is good, or even a lens cap. But a ruler is best of course.
And size varies. Eucalypts are a good example. Leaf shape, length and width are all important features, yet for most species their leaves will vary significantly in both dimensions. Take measurements of multiple leaves, trying to 'capture' the full range. OK, a ruler really is a must for field work.
When examining or photographing delicate species, take care. Orchids are particularly susceptible to damage. Avoid touching the plant at all .... and check what you're kneeling on, as where there is one there are often more. Many orchids are declared protected species, and for good reason.
Tip 3 – Stop and think before picking a plant
There are several things to consider before collecting any physical samples. First and foremost: "Can I simply take photos instead?". If you think these may not be enough for a good identification, then ask yourself: "Where am I?" Collection is prohibited from many places, including all floral reserves and national parks. And finally: "Is it a protected or threatened species?" Become familiar with the list of protected and threatened species for your region and check on any regulations and licence requirements.
Tip 4 – Find a local field guide
A simple web search may uncover all you need. Alternatively, search iNaturalist for your area. Or contact your nearest Botanic Garden or native plant society.
Tip 5 – Beware common names
Avoid dependance on common names – they are unreliable. Any common name is likely to be used to describe multiple species, depending upon where you are and who is speaking. And any particular species is likely to go by several different common names ... again, depending upon where you are and who is speaking. Scientific names, however, are absolute.
Tip 6 – Locate a plant key
We make extensive use of Plantnet and VicFlora. Both online resources are comprehensive, providing detailed descriptions, distribution maps and keys for all vascular plant species in their respective states.
Plantnet: NSW Flora Online VicFlora: Flora of Victoria
Tip 7 – Use a dissecting microscope, or at least a hand lens
Some of the structures described in a key are small and internal. You will need to magnify the object and to 'dissect' it. A dissecting microscope is an incredibly valuable tool. We use ours all the time! See our Identifying invertebrates page for more discussion on choosing a microscope.
Warning! – the truly systematic approach is not for the faint-of-heart. It requires a good deal of background botanical knowledge, depending upon the level of classification at which you start and the group you are working on. If you make a mistake at any step in the key – and it will happen from time to time – you end up in a blind alley and need to backtrack. It's all part of the fun.
Tip 8 – Identification to genus is a worthwhile goal
For some genera, the target for identification is obviously the species level ... otherwise all wattles are simply Acacia sp., and banksia are simply Banksia sp.. But for other groups, identification to genus is a worthy goal. There are 140 genera of 'peas' in Australia (subfamily Faboideae) - distinguishing Pultenea sp. from Dillwynia sp. is therefore an achievement in itself.
If, at the outset, you are confident of the family of your candidate plant, an alternative approach is to do a Locality Search. Both PlantNet and VicFlora offer the option of filtering by location. Be aware that such lists are sometimes incomplete - particularly if you choose a small radius in the PlantNet filter – but it’s a good place to start.
You then work through the descriptions and/or images of each species on that locality list to find one that matches your plant. How useful this method will be depends upon how many species you end up with after your locality search – 10 candidates is workable, 50 less so.
Of course, all of this supposes that you are in fact looking at an Australian native plant growing in its 'normal' environment. If you have a garden escapee .... hhmm, a problem.