Jerry's censuring of my English in another thread, lead me to consider more closely what is going on in phrases like "this sort of tree". Consider these combinatoric variants:

a. this sort of tree
b. this sort of trees
c. this sorts of tree
d. this sorts of trees
e. these sort of tree
f. these sort of trees
g. these sorts of tree
h. these sorts of trees

Some only allow (a), but colloquially I allow both (a) and (h). I hear (f) often enough. The construction itself goes back to about the 16th century in British English, and Fowler says of it: "& nearly as easy to forgive when they deserve forgiveness, i.e., in hasty talk". What a kindler, gentler usage maven Mr Fowler is than the likes of panda-shooting L. Truss and yours truly in all their dyspeptic glory. I must admit that (b) - (e) and (g) sound bad to my ear. It's (f) that I find interesting. It's hard to tell if I use it myself when speaking, but it doesn't sound that bad. For at least a century people have been using kind of (kinda) and sort of (sorta) as adverbs, as in "I kinda hope he's wrong", and so it is easy to see why kind/sort might not take a plural marker in the case of "these sort of people". It's not really a matter of grammar, because (a) and (h) are grammatically correct, (f) seemingly less so, but what about phrases:

i. trees of all kind
j. trees of all kinds

For me, (i) is wrong and (j) is right, but others may differ. Thanks, JT, you gave me a good think.

To my eye and to my ear, (a), (h) and (j) are the only ones that seem right. Take that with a grain or three of salt, though, since I'm no grammar maven.

quote:

Jerry's censuring of my English in another thread,

Hmmm, I was gone for the weekend and missed that thread. I will have to look for it.

I agree with Asa in his selection of the ones that sound correct, and, as Asa, I am not a grammar maven, either.

I have learned a lot from this site, though, about grammar mavens. From what I have seen, those who complain about intricate misuses are, themselves, often ignorant of how writing and grammar evolves. For example, there are still editors who say that you can never use the passive voice. I wonder what the point of it is, then.