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When growing plants it is useful to know some of the scientific terms and how they work to make things clearer when we are talking about plants. The sky is the limit here, but there's no need to go crazy with in depth anatomy and reproduction systems etc. A few basic things can be helpful and interesting, and further your enjoyment  of plants.

Linnean Classification System

Who was paying attention in biology class?! When I was at school (........) all living things were divided and classified by the Linnean System-essentially seven increasing groups, of of an increasing level of accuracy to identify each species we have found- Kingdom, Phylum (Division when talking about plants), Class, Order, Family, Genus and Species.

This has now been changed to a much more detailed and complicated system, but as we really are only interested in the last three classifications (Family, Genus and Species), let's stick with the Linnean System...

It sounds complicated, so to break it down, let's do an example and explain each category a bit. In this instance, we'll look at   Cypripedium calceolus, the Lady's Slipper Orchid, and see how each step narrows down it's identification;


Kingdom-Plantae.....pretty obvious this one...another Kingdom would be Animalia (these really are the two main Kingdoms)


Division-Magnoliophyta...simply, this means flowering plants, and therefore seeds (this has been split to more levels now, but of no concern to us...). Other types of plant that reproduce by different means (Ferns for example reproduce by spores) fall under a different division (for Ferns, 

Class-Liliopsida... this was called Monocotyledoneae in my day!.....this refers to how the plant grows at the time of germination. A cotyledon is the first leaf produced by the seed-monocotyledons have one cotyledon when they germinate, dicotyledons have two.....imagine a grass seed-this has one leaf when it germinates so falls under the Order of 'Lilopsida' (monocotyledon....we'll just call it this, they'll change Lilopsida again soon so let's just make it easy).  


Order- Asparagales...this used to be Liliales and where it gets a bit too technical, and where the real scientific divison of flowers starts.....the basic gist is that Liliales have flowers with colourful tepals and lack starch in their endosperm.....I don't know what that means either. This is really stuff for taxonomy and scientists, and not too important for the keen horticulturalist. we go, something we of relevance to us and that we can work with-the Orchid Family! All plants in this family have the basic flower structure of an 'Orchid'-technically, this is a three petalled flower with the middle petal enlarged into a lip is now split down further into to Genera....when lots of species are closely related, they fall under the same Genus. There can be many species under one Genus, but they all share similar characteristics.

Examples of some other Orchid genera you might know would be Phalaenopsis and Dendrobium

Species-calceolus....this is the detailed specific description of this particular plant, this 'species'. It looks at how it grows (height, habit, leaf structure), how it flowers (if the flowers are borne singularly, in pairs, clusters, on stalks or not), flower colour, flower scent, where it occurs geographically and also at what altitude (very important when trying to identify Alpine species!), and sets it apart from other species of the same genus.....all of a sudden the term 'be specific' makes more sense!


Got it?!

You can see that the main three categories we are interested in are the plants family, the genus and the species (the genus and species are collectively known as the Binomial System-more on this shortly.


Looking at plant families can be really interesting, and it is often surprising which plants are closely related....and then sometimes, it's like 'oh yes, of course'!


Let's look at the Rose Family (Rosaceae) for example. The classic rose flower we all know is more or less a human invention (more on this later), and in the wild they grow as singles-some of you might know Rosa rugosa, which is a common cultivated species Rose......remind you of anything?!    

Would it then surprise you to know that Strawberries (Fragaria) are in the same family? When you look at the flowers, it's obvious!

Here are a few more common things we eat everyday that we'd probably never think of as being 'roses';

Apples, Pears, Cherries, Nectarines, Peaches, Plums, Raspberries, Blackberries.....Pomegranates (!!! check out a rose seed head, a 'rose hip' hip....looks just like a mini Pomegranate!).....makes sense once you know right?! Interesting that many members are fruit bearing (of course man has selected and improved things like Apples...a Crab Apple is more the size you'd expect to see in the wild).

Here's another good one, the Umbels (Umbelliferae), of which family the carrot belongs to. Have you noticed the carrots foliage before? Remind you of anything?!


Here are more family members;

Parsley, Coriander, Celery, Celeriac, Cow Parsley, Carraway Seed, Star Anise (ever seen a carrot or Cows Parsley go to seed? Look just like a mini Star Anise)

Try rubbing a carrot's foliage next time you see some-it gives off an aroma very similar to Parsley. In-fact, when you know, you'll notice that all the seeds and flavours have a connecting 'taste frequency' that you can recognise them by, and again, interesting that we eat a lot of this family.

Right, starting to get the gist now, one more before we move on....the Mint Family (Labiatae), one of the defining features is that they are all square-stemmed-check some next time you see some, it really is incredible;

Mint, Thyme, Oregano, Marjoram, Sage, Lavender, Rosemary



The Binomial System

Ok, you're getting good, you can recognise plant families and understand what that means, you're officially a Botanist.

Let's dig a little deeper.....

After the Family, we come to the Genus. Let's have a quick look at the Genus Primula.

Primula are from the family Primulaceae. The genus is made up of around 400 species that occur in a range of different habitats, mostly in the Northern Hemisphere, but some in the Southern. Almost half the species come from the Himalayas. 


(another family member you'll probably know is the genus Cyclamen-it's sometimes difficult to see, due to the swept back petals of the Cyclamen, but if you turn the flower upside down then push the petals forward, it actually looks like a giant Primula flower!).


Let's now look at three Primula species native to the UK that you'll know (well...hopefully you'll know- I guess if you've read this far you're interested enough in plants to know a couple of these!) so we can start joining the dots;


The Cowslip- a common plant offered in Garden Centres and growing in woodland, hedges and by the sides of motorways in early spring. This is Primula veris. 

The Common Primrose- another one that puts on a great display on the M40 verges, with it's crinkled grey green leaves and pastel yellow flowers close to it's heart...this is Primula vulgaris (vulgaris means 'common' in Latin....more on that later) 


The Oxslip-not as common as the Cowslip (P. veris), a hairier softer plant with fewer and larger flowers, this is Primula elatior.

Easy right?! 

There are further divisions (sub species, variations, named forms, selections....but we'll come to that later.


There we go, it's not complicated at all, and really very interesting. Let's take a quick look at Nomenculture-a posh word for naming plants!

Why do plants have the names they do?

On the whole, plants are names are derived from Latin or Greek, and can describe the habit of a plant (for example, the genus Campanula... campanulate means 'bell-shaped', and the common name of this genus is the Bell Flowers, as on the whole they have....bell shaped flowers!) where they occur (Campanula alpina-occurs in the Alps), those that discovered them (C. zoysii-discovered by Austrian botanist Karl von Zoys), or in tribute to people...... Lewis and Clark, the explorers who 'discovered' America had two genus named after them-Lewisia and Clarkia. (I don't know much about Clarkia, but Lewisia is a fantastic genus, with succulent-like leaves formed in rosettes bearing showy waxy flowers from rocky areas of North America.)

Specifically, the name can highlight a defining feature......

Here's a good example-Pyrola rotundifolia......'rotundifolia' is easily recognisable to us as being 'round leaved'. This sets it apart from other members of the genus, and if you were out plant spotting would enable you to identify it.

Other times, a plant can be specifically named because it resembles another Genus. Sometimes the genus name has been used exactly as it is (Saxifraga sempervivum), but often there's an abbreviation of the generic name and the addition of 'oides'.

Here's an example;

A common Alpine you see offered at Garden Centres and growing in rockeries and tumbling over walls everywhere, easily recognised by it's soft-felty light grey foliage and upright white flowers, Cerastium tomentosum

Here is a Gypsophila- (all you plant fanciers will recognise Gypsophilla as it's often sold at's far to tall for my liking),  but it's a good example...anyway) this one forms a low growing mat, and it's flowers and over all habit look very similar to that of a Cerastium' it was named Gyposphilla cerastoides. Suddenly the plant naming world feels a bit smaller and easier to remember. 

Sometimes, the name comparison is not to another plant, but an animal or insect!


Sempervivum arachnoideum, the Cobweb Houseleek looks like a spider has spun it's web in the middle of it's rosette

Orchis simia (Simian is the Latin for Monkey), the Monkey Orchid has flowers that resemble a monkey!

So..... let's apply this wealth of knowledge, and let's get relevant!


I know you're all avid Orchid fans, and pretty sure that if you've bought or been given an Orchid, it's from a supermarket or garden centre, and it's probably the most common (but no less wonderful-there's a reason it's 'common') Orchid offered, the Moth Orchid.... which as botanists we now refer by it's proper Latin name-Phalaenopsis (Phalaenopsis is the Genus).  

In certain Garden Centres (writing from the UK), there now seems to be quite a diverse range of Orchids being offered, perhaps due to the recent surge of interest in gardening. You can often find Dendrobium (Dendrobium nobile 'Spring Dream' with it's large, scented showy white flowers on bamboo-like canes also appears at supermarkets) species, Epidenrum, Cambria (this Orchid 'generic' name is slightly confusing as it's a name lumped on to all the offspring of hybrids from three Orchid genera-more on this later) and Miltonia (as with Cambria....) 

Anyway, of course, you have a Phalaenopsis, more than likely several..... you know it's round Moth-like happy little flowers, and probably because you're a proper Orchid obsessive you've also got a Dendrobium - probably D. nobile 'Spring Dream'...

Then you're wandering around your Garden Centre itching to make a purchase and a load of new Orchid stock has just come particular type stands out, and has some features you kind or has the cane like habit of Dendrobium nobile, but it's flowers aren't borne in little clusters as side-shoots from the cane, they rise up one one single stem, and are bigger, and look much more like your Moth Orchid.....well, what you are seeing is Dendrobium phalaenopsis!! Cool huh?!

Why then, you might ask, is it a Dendrobium and not a Phalaenopsis? It is because the anatomy of the plant fit's into what they have classified as a Dendrobium-it has a sympodial (spreads by a horizontal rhizome which forms clumps of leaves......Phaleanopsis are monopodial-they produce new leaves from a central crown) habit, and forms elongated, stem-like pseudobulbs. With your new plant knowledge, you now know of course that the fact that the way the flowers are borne and their appearance is similar to a Phalaenopsis is because they are closely related plants from the same family.....!


N.B (Well, pretty much....'Sa-nook' is the one you'll see, and it's a hybrid, but resembles very closely it's main parent, D. phalaenopsis

Sub species, Varieties, Selections, Named Forms and Hybrids

Botanists are a funny lot, they'd divided themselves into two groups;

'lumpers', those that want to say any species can be variable so differing versions are probably just seedling variations of one main species, they want to 'lump' all variants together, and... 

'splitters', who want to classify every variation as a separate species.

They argue about it foir hours...then they change it all again. While making sure my facts are correct for this page, I've discovered they've now moved Campanula zoysii out of the genus Campanula and given it it's own genus, Favratia. Ridiculous.

Personally, I don't believe in any of it-if you believe in evolution how can you one species is a defining version?! It evolved from something else and will evolve in to another plant....the names, labels we are giving these plants are just a snap shot. Anyway, that's another story.... Let's look at Sub species etc.  

Sub species and varieties (abbreviated to var.) are really more scientific terms that the collector or identifier in the field would need to know. The other terms are more useful to use in understanding exactly what it is we are looking for, buying, and trying to care for;

Selections-these are usually just the best forms from seedlings that the grower will 'select' and cross pollinate with other selected forms to keep and improve beneficial characteristics. Often plants now that we see in Garden Centres and Nurseries are nothing like the plant that occurs in the wild (the true species), as more vigorous plants with larger flowers have been selected. The Pasque Flower, Pulsatilla vulgaris (it's not common anymore....), which still grows wild in the UK at a few sites is a classic example of this. The true species is a dainty little plant, forming a neat tuft of grassy green carrot-like leaves, with a few flowers no taller than 6 inches. The cultivated form of P. vulgaris (when there is this difference between wild plant and cultivated, the cultivated plant is referred to as 'of gardens') although still lovely, is a boisterous brute of a plant, throwing out 10s of huge violet star-shaped urns on stout silky stems, and forms a sizeable clump! It also has a red flowered form-P. vulgaris var. Rubra and a white flowered form, P. vulgaris var. Alba. Note the use of 'var' here...   

Named forms- A grower can take a particularly distinct form of his plant, and try to get it recognised as a named form. When this happens, often the specific name is dropped. These plants can just be a selection as described above, but often the plant has hybridised with another closely related plant. They retain most of the features of their main generic parent, so keep the generic name, but are different from any of the species (and usually not naturally occurring....for instance, imagine two Orchids kept in a growers greenhouse-one is from Asia, the other from South America-the two would never naturally meet, but as they are closely related can reproduce) so take on the named form. The Dendrobium we mentioned above is a good example of this, Dendrobium Sa-nook, -although basically a D. phalaenopsis, it is a hybrid and distinct from the species. There is a crossover here, and D. Sa-nook could also fall under the term 'hybrid'.

True Hybrids-as you have seen, hybridisation does occur, and when it produces something that is completely different to any parent (hybrids can be a few different parents across a few generations....imagine two mongrel dogs offspring), it stands alone as a true hybrid plant.

Cambria Orchids are a good example of this. It is a trigeneric hybrid of Odontoglossum, Miltonia and Cochlioda. They are collectively called 'Cambria', althogh their given generic name is Vuylstekeara, named after the nurseryman Charles Vuylsteke. Vuylstekeara cambria 'Plush' was the most famous hybrid, so they have been known as Cambrias eversince.   

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