Symbols used in Headings
The name of a plant is at the top of a page and in the case of plants in the UK has symbols next to it and example would be:
Gentiana verna Spring Gentian RR DD N
Rarity
The first symbols using RR denote rarity. I use the system in Professor Clive Stace's books New Flora of the British Isles Edition 3 published in April 2010. Updating the rarity symbols began on April 18th 2010 but will not be complete for a year or so.
R - Uncommon. Plants found in not more than 250 of the 3859 10x10 km grid squares of an OS map (about 6.5%).
This does not rule out a high local concentration within a square though. To give an example Limosella aquatica (Mudwort) is a rare plant and so rates theRR symbol but in a good year around the edge of the reservoir where the plant illustrated was found there were so many thousands that it was not a rare in the accepted sense. This plant likes to populate the muddy edges of ponds, lakes and particularly reservoirs in late summer so would only be found where these conditions prevailed. There aren't large numbers of 10x10 km square with Limosella aquatica in them but where it is present it can be abundant with literally millions of plants to be found.
RR Plants found in not more than 100 of the 3859 10x10 km grid squares of an OS map (about 2.5%).
RRR Plants found in not more than 15 of the 3859 10x10 km grid squares of an OS map (about 0.3%).
This RRR symbol also denotes rarity and vulnerability and these plants are listed in the Schedule of protected Plants part of the Wildlife and Countryside Act of 1981. I also use the symbolRRR to denote very rare and vulnerable plants which aren't in Stace's excellent books but ought to be classifiedRRR . He doesn't list all Hieracia, Rubus or Taraxacum for instance so rare plants of these genera aren't classified.
Find list of 1981 Act plants here.
Common Plants
This is the opposite of rarity. Just as some plants are very rare and vulnerable some are as common as muck. Gardeners usually classify wild plants which have colonised their flower beds as weeds. There have been many occasions when puzzled passers-by have asked why I'm photographing weeds. You can try explaining that weeds are just wild plants which are successful colonisers of any empty space with a bit of soil but you'll usually be met with an incomprehensible look.
A rose in a cabbage patch is a weed. A cabbage in a rose garden is a weed. Cabbages and roses which have escaped by natural means (i.e. not planted) into the countryside are wild plants albeit not native wild plants.
A plant with aC symbol is found here and there. It might be common in one part of the country and not in another but exists in many more than 100 of the 10 km squares. Most countryside plants like Primula vulgaris (Primrose) or Hyacinthoides non-scripta (Bluebell) would have this symbol.
A plant with aCC symbol might be very common but still not quite in every square whileCCC is the dead opposite ofRRR . You can find this plant almost anywhere except perhaps at the top of a mountain in the Cairngorms.
Difficulty of Access
The next set of symbols are my own and are a rough indication of how easy or difficult it was to find the plant or how common it is (usually for me). This varies over the country of course. It would be fairly easy to see Primula scotica if you owned a holiday cottage somewhere near Strathay Point where it grows in the thousands but if you live in Kent a major journey would be needed to find it.
So this is merely my own personal experience.
A plant withD beside it was very easy to get to. Such plants would be Stinging Nettle or Daisy. You only have to step to an area of unused land or even into your own garden to find these sorts of plants.
A plant withDD beside it is one you had to walk a small distance to find. If you travelled by car to the limestone areas as I have to, then you would still have to get out and walk into the countryside to see the plants. Most plants will have this rating. Some plants, even with anRRR rating, can be surprisingly easy to get to. An example would be Simethis mattiazzii (Kerry Lily) which is only found on one part of the Ring of Kerry in the Republic of Ireland. You can drive to within 100 metres of this very rare and vulnerable plant although because it's quite small it needs to be sought out.
A plant withDDD is usually very difficult to get to where ever you live. An example would be Saxifraga cernua (Drooping Saxifrage) which grows at the top of a few Scottish mountains so you usually have to climb a Munro before you can even start looking.
You even argue aDDDD rating for special plants like Diapensia lapponica which grows only at the very top of one mountain in Scotland. There are no paths leading to the 2,800 foot summit and you have to start low down not much above sea level. The mountain is frequently shrouded in mist and the flower only opens in sunshine. To add insult to injury it has a short flowering period. This one is extremely hard.
Equally tough are plants in the middle of midge ridden bogs or on cliffs like Gagea serotina (Snowdon Lily). Of course it's always possible to find the odd plant which should grow at the top of a mountain somewhere much easier to access but beware - wardens sometimes plant examples of rare species in low easy to find places so botanists won't disturb the main colony at 2,000 feet. If you are not reasonably fit don't attempt to find these sorts of plants you might die in the attempt.
Natives and Introductions
Our flora is still recovering from the last Ice Age (Cold period) 12,000 years ago and so new plants sometimes find a suitable ecological niche in a locality or even the country and come so stay. An example of such an introduction would be Epilobium brunnescens (New Zealand Willow herb). You find this on most mountains in the UK now but it wasn't always part of our flora so it's given anI for introduction. Some introductions are rare and others are common but generally I don't rate introductions for difficulty or rarity.
About 9,000 years ago sea levels rose and the Island of Great Britain was formed as this land became cut off from mainland continental Europe. Our native plants are those that were (believed?) present in the British Isles before the formation of the English Channel and they are given the symbolN for native. Since then a few plants new to our flora have arrived on the Island by natural means not as garden escapes or introduced by humans. These are also natives.
How do we know whether a plant is native or not?
First we must identify it correctly which, as Dr Peter Sell pointed out in BSBI News April 2007, isn't as easy as it seems because there are so many foreign plants (Introductions) which look superficially exactly the same as the assumed native one. He calls these "Look alikes". He cites early flowering Primroses and Cowslips which are probably not native. Unfortunately ordinary botanists don't have access to the books and herbarium specimens needed to make such subtle but important distinctions so we shall have to continue in our ignorance.
To add further confusion, evidence from historical records researched by Pearman [Watsonia 26: 271-290 (2007)] shows that some plants long assumed to be native such as Fritillaria meleagris (Fritillary) are possibly introduced. It seems that in the 17th and 18th century some rather attractive plants were deemed to be native in certain parts of the country because local botanists wanted them to be! Many botanists disagree with this treatment so again you can legitimately classify Fritillaria meleagris (Fritillary) as native or introduced.
In his article Dr Sell who died in 2013, actually proffered the opinion that there aren't many truly native plants in Cambridgeshire where he lived and botanises and that only by mountain streams, beaches or other such habitats might we find true natives. Perhaps there aren't any natives at all in the UK but for the time being I use Stace's classification amended by any information which BSBI releases about this interesting topic.
I could have discriminated further by labelling some plants as transient aliens. These plants appears from time to time in different places but don't stay. On this site all plants not deemed native by Stace are introductions of some kind.
Endemics
A few plants are endemic to an area whether a part of the British Isles, a part of Europe in the European flower section or an Australian endemic of which there are many. They are labelled Endemic
Very Small Plants
Some plants are so small that you can't see them when standing up and even when kneeling it's quite difficult. Such plants are sometimes labelledelashr. Such plants really cannot be seen unless kneeling down hunched usually with a magnifying glass so the usual botanist's pose standing with hunched shoulders peering at shoes from a height of five to six feet won't work.
Examples of such plants are Koenigia islandica (Iceland Purslane) and Ophioglossum lusitanicum (Least Adder's-tongue).
Australian flora
The Australian flora is not yet completely characterised and so if a plant of known genus but unknown species rank is encountered the symbol aff. is used. An example might be Diuris aff. corymbosa which indicates that the species is a Donkey Orchid (Diuris) of unknown species but something like the known species: Diuris corymbosa. 62% of the western Australian flora are endemics.
Added on 8th Feb 07, amended 27th Sep 07, Oct 16th 07, May 1st 08, corrected/validated 18th Jun 08, updated Se3 22nd Apr 2010, Sep 22nd 2017, Aug 2018