In message , gray
writes
All right then.

Whats the difference between the 3 main 'wild' roses. Differences that
are easy to spot.

There's not necessarily easy to spot differences for all the rose
species -

The 3 are sweet briar rose, field rose and dog rose ???

but if we restrict the scope to these three, then

Rosa arvensis (the field rose) has the styles fused into a column more
or less as long as the stamens. (The other 4 species with fused styles
are rare.)

Rosa rubiginosa (sweet briar) has strongly scented foliage; I presume
that Rosa canina (dog rose) doesn't. Rosa rubiginosa has erect stems,
Rosa canina arching stems.

[Data from Stace; Keble Martin; and Clapham, Tutin & Warburg.]
--
Stewart Robert Hinsley