In article , Brian
writes

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I agree that a key for cultivated plants would be impossible. A
help to group them is quite often found and then the encyclopaedia assists.

Yep. Same way as using taxonomy to identify a wild flower. Easy enough
to get the hang of most of the families found in the UK, but more
difficult with garden plants because a) they're species from across the
world and may be from a family not represented in UK b) there are so
many hybrids and particularly double flowers which make it hard to
identify the family.

So grouping by growth form, flower colour and season of flowering does
seem quite useful.

For wild plants I use Clapham,Tutin & Warburg~and can still get
lost. It is totally comprehensive and is the 'bible'.

It used to be the bible, but I gather Stace took over about 10 years
back.

It has very few
illustrations. However I understand the point you make~~if one can
understand the use of a complex flora then it is quite likely that you don't
need a flora at all!!

Well, I wouldn't say that! Rather that your knowledge and interest in
botany exceeds mine by rather more than mine exceeds that of the 'man in
the street' ;-)

Certainly with a flora you need the specimen in front of you and a hand
lens. Whereas if you see, say, grass of Parnassus, for the first time on
a long walk, you can come home with a strong visual memory and perhaps a
few pencilled supplementary notes and identify it from a good
illustrated wild flower book, whereas you wouldn't have a hope going
through a key. And if there is a closely related almost
indistinguishable species recorded from 3 locations above 1200 feet, a)
it's unlikely that that's what you saw and b) is your level of interest
*really* that strong?

Generic you of course, not you specifically !

Though I have to admit that, while I arguing in favour of an illustrated
guide in which the flowers are arranged in taxonomic order, I hate
guides where the wild flowers are ordered by colour of flower! Yet
arguably that could be useful for someone whose interest is less than
mine.
--
Kay
"Do not insult the crocodile until you have crossed the river"