A short EUCLID key tutorial

This section shows how EUCLID works, leading you through a tutorial to identify a eucalypt using only a few characters - leaves, fruits and buds.

The tutorial images below, are of a southern bluegum or Eurabbie (Eucalyptus globulus subsp. bicostata), naturally occurring in south-eastern Australia but widely cultivated across southern Australia. Using the information in the pictures you should be able to identify this species using EUCLID. This tutorial takes you through the steps you would need to follow to do this, if you were running the package.

Tutorial images


EUCLID front page1. Start EUCLID by double-clicking its icon on your screen.

2. Once the EUCLID front page is open, click on ‘Identify a eucalypt'. This will open a screen showing four windows and a tool bar. The windows initially hold two lists Taxa Remaining and Characters Avaliable, see below.

Opening screen of EUCLID

Character sets3. You should start your identification by limiting your Characters Available list to only those characters relevant to the four tutorial images above. These images have information about leaves, inflorescences, flower buds and fruit so it is no use looking at characters such as habit or bark. You can select your set of characters by clicking on the Sets button from the tool bar near the top of the screen. From the window that pops up, select your set of characters by ticking the ‘Leaves', ‘Inflorescences', ‘Flowers and buds' and ‘Fruit' boxes.


Your Characters Available window should reduce from 120 to 61 characters.

Characters Available - 61

4. From the Characters Available window, scan the list of characters for one you think you can answer. We suggest that you try the character Leaf blade shape first.

5. Click with the mouse on the text of the character Leaf blade shape. It will open up like this:

Leaf blade shape

In our case, the image of the leaf shows that it is falcate (sickle-shaped or curved). If you want to check, click on the button beside the state sickle-shaped or curved. A window appears where all the shapes are illustrated as line drawings, and each accompanied by a brief definition.

Leaf blade shape notes

6. The state falcate (sickle-shaped or curved) is your answer to this character. Choose it by either:

Leaf blade shape - 456 taxa remaining

7. Look at the list of Taxa Remaining (above). You will see from the window that there are 456 taxa with sickle-shaped or curved leaves. Still a way to go, but note that this one character has eliminated 438 taxa (listed in Taxa Discarded).

8. Try a metric character next. The leaf pictured in the tutorial images is 30 cm long and 5 cm wide. Choose the character Leaf blade width. After double-clicking beside the symbol #, a small window like this pops up:

Leaf blade width

The window tells you the range of values that are possible for this character – in this case, no species in the remaining set of 456 taxa has leaves narrower than 0.3 cm or wider than 7 cm (this is useful for giving the absolute outer limits for your answer). Type into the box the value 5 and click on the OK button. You will see from Taxa Remaining that we are now down to 35 taxa.

Leaf blade width - 35 taxa remaining

9. Now try the character Number of buds or flowers per umbel. In eucalypts, the umbel is the unit cluster of buds or flowers. The tutorial images above show that there are three buds per umbel. As before, double-click or drag the words three-flowered to make your selection. You are now down to 8 taxa.

Number of buds or flowers per umbel - 8 taxa remaining

10. Where do you go from here? Let's say that you're stuck, and want to ask the key to suggest the best character to answer next. You can do this using Lucid's Best function. Best button

You can use Best in two ways. The first is called a Sort Best, and will sort all the characters in Characters Available, from best (most discriminating) to worst (least discriminating). The second is called Find Best. Rather than sorting all the characters (sometimes a slow process), Find Best goes to, and opens, the best character. Two buttons appear on the toolbar which allow you to go forward to the next best or back to the previous best character. Note that Best is usually used when you are some way through your identification, so that the list of Taxa Remaining is fairly short. Find Best is faster than Sort Best.

Best function

So, let's try a Sort Best, since we only have a few taxa remaining. First, check which Best option is current – go to the Characters menu and click on the item Best Options. The current option has a checkmark alongside it (if Find BEST character has the tick, click on Sort Characters on BEST).

Best button   Now click the Best button on the toolbar. Wait a little while Lucid assesses, then sorts, the characters.

Once the sort is complete, you'll see that the character Fruit width is now at the top of Characters Available. This means that entering a numeric value for fruit width will, on average, reduce the list of Taxa Remaining by the greatest amount, so you will close in on your identification fastest. Note from the tutorial images above that our species the fruit is 1.8 cm wide at its widest point, we are left with 3 taxa.

Fruit width - 3 taxa remaining

11. Lets try the leaf petiole (leaf stalk) length of 5cm next to see if we can reduce the list further - and presto we are left with one taxa remaining Eucalyptus globulus subsp. bicosta.

Leaf petiole length character image

Leaf petiole length - 1 taxa remaining

12. Now look at the accessory information for our species, by clicking on the button alongside it. Open up the Notes and click on Fact Sheet to read the description to compare it with the pictures we started with, or look at the EUCLID images of the species. If the accessory information matches, then you can be confident that you have correctly identified your species.

Additional information


Fact Sheet