In article ,
Mike Lyle wrote:

Thanks for that. Collins lists D. tenuifolia as "Perennial wall
rocket". Another species, D. muralis or Annual wall rocket appears in
the same paragraph. No sign of D. erucoides under that name. Back to
the Internet!

Having checked up in Culpeper, CTW, the OED etc., the situation is
as follows:

The rocket that supermarkets sell has been called rocket or
garden rocket (I was wrong about sweet rocket), and is Eruca sativa
(Brassica eruca etc.) We all agreed on the last.

The term "rocket" has been applied, with or without qualifications,
to at least 6 genera of brassicas, including all those mentioned, plus
Hesperis and Barbarea. Like most common names, it is "loose".

Interestingly, "blue rocket" has been applied to aconite,
delphinium and bluebell (two of which are seriously poisonous), and
there are several other non-brassicas called rockets.

The term "wild rocket" has been applied to a fair number of them,
including at least Sisymbrium officinale, but I believe that the
supermarkets have invented it as a marketing term for another variety
of Eruca sativa.

So there is no reasonable sense in which it is a common name for what
the supermarkets are selling, unless I am wrong and they really ARE
selling Sisymbrium officinale - and what I saw sold as wild rocket
was definitely Eruca sativa ...


Regards,
Nick Maclaren.