A note on wildlife classification

How we have structured our species list

On this page we will explain which classification systems we are using to organise our species records. Appreciating how species relate to one another is often helpful when developing identification skills. It is also interesting and often surprising to learn how some species are more closely related than others. For example the shade tolerant plant Lords & Ladies, is closely related to the Duckweed you find carpeting ponds.

The simplest classification system, and the one we are most accustomed to, is the Five Kingdom Classification. Although viewed by many as out of date, especially since genetic information has become more economic to gather, it is still a very useful and relatively accurate system for our purposes.

It places all life on earth into one of the following five Kingdoms

Animalia, Plantae, Fungi, Protista and Monera

Each Kingdom is subdivided into smaller and smaller groups of more and more closely related species. To better illustrate this lets take the Common Blackbird as an example. We all know it’s an animal, so along with every other animal on the planet it has been grouped into the Kingdom Animalia.

The animal kingdom (as are all five kingdoms) is then subdivided into Phyla. The animal kingdom has many phyla but most animals belong to just one of the following seven;

Porifera, Cnidaria, Platyhelminthes, Annelida, Mollusca, Athropoda and Chordata

Only animals with a backbone will be found in the phylum Chordata, which is where our blackbird resides, birds having a backbone just like humans (also Chordata). But clearly birds and humans are not the same, and so it is that each phyla is subdivided again into Classes and it is at this level that humans and birds part company. Humans fall into the Class Mammalia, where as our Blackbird finds itself grouped with all other birds in the Class Aves.

Birds come in all shapes and sizes, clearly having evolved in many different ways and some are more closely related than others. So Class Aves is further divided into groups know as Orders, and our blackbird resides within the order Passeriformes (Passerine birds).

But still there is further subdividing we can do and beneath the Order Passeriformes are a number of more closely related species divided into Families. In this case the family Turdidae. At the time of writing this article our species list contains two representatives of this family, blackbirds and song thrush. Indeed Turdidae is known in English as the Thrush family.

As we all know the Latin name for any species is unique to that species and comprises (most the time) to two names. The first is the Genus name and here both the Blackbird and Song Thrush share the same Genus (first) name, the not very apt Turdus. Species within the same Genus are as closely related as can be without actually being the same species. The second name relates specifically to the individual species and it is the combination of these two Latin names that is specific to each species. In this case Blackbirds are Turdus merula, while Song Thrush are Turdus philomelos. Note Latin names are nearly always written in italics and the species (second name) never starts with a capital letter.

So here it is, the blackbird classification in full…

Animalia (Kingdom), Chordata (Phylum) , Aves (Class), Passeriformes (Order), Turdidae (Family), Turdus (Genus), merula (Species) – Blackbird

Every individual animal is classified in a similar way, belonging first to a species with which it can produce offspring, then to a genus of very closely related species, then a family, then order, class, phylum and finally Kingdom. Our Animal species list follows this structure, although it is far from complete and will remain a work in progress.

But what about plants. Well, these too can and have fitted nicely into the Five Kingdom Classification system. However since the 1980’s/90’s classification of plants, in particular flowering plants, has undergone several revisions. Much of which is now based on molecular/genetic data. Indeed so much revision has occurred that it seems rare now to see the formal use of the 5 Kingdom Classification system.

The new system, which we don’t pretend to fully understand, is termed APG IV, which is the 4th version of the Angiosperm Phylogeny Group System. And whilst many of the levels of classification remain from the Five Kingdom system, such as Order, Family etc. there are often levels / or ‘clades’ in between to help further separate species into even more closely related groups. It’s very complicated and to demonstrate this we took all 46 plants recorded in our garden (as of Sep 2022) and using a simplified version of the APG IV system ended up with the following…

The bottom row shows all 46 species. The black circle in the top row simply states ‘Plants’. All 46 species can trace their way up through the classification system to ‘Plants’, in other words they are all Plants.

Most species are underlined in yellow or orange and can all be traced back to a shared meeting point highlighted by the pink star. This box is called ‘Angiosperms’, which simply means Flowering Plants. Only species that can trace their way from the bottom row up to the Angiosperm box are flowering plants. Those underlined in blue and green do not approach pink from below and are therefore not flowering plants, but more on them below.

Angiosperms are then divided into Eudicots (Yellow Circle), which used to be called Dicotyledons (having two seed leaves) and Monocots (Orange Circle), which used to be called Monocotyledons (having one seed leaf). In our gallery/species list we have used this level to divide the flowering plants, rather than have one massive group containing both.

The Blue Circle simply shows the lineage of Ferns, which are not flowering plants but can trace back to the level marked with a brown star called Tracheophytes, or in old botanical terms Vascular plants. All vascular plants have tubes called Xylem and Phloem, that transport water, minerals and other necessary substances up and down the plant. Both flowering plants and ferns share this characteristic.

However note the Green Circle. This highlights the lineage of mosses. It cannot trace upwards to either the pink or the brown stars (it is not a flowering plant and it does not have vascular plant characteristics). Whilst mosses are plants, they share no direct lineage from vascular/flowering plants.

What about the two other kingdoms of life we have recorded in the garden? For now we have decided not to subdivide them to any great extent as there are very few fungi recorded to date and only one moneran. If the species lists for these kingdoms grows then we may decide to separate them into more closely related groups using a suitable classification system.

DC – 19th September 2021