Thanks, Waltraud! I spent ages trying to work our which Verbena it was ... thought the flowers looked wrong, but a bit wilted because late in the day or something. But the species name shows it is a Salvia which looks like a Verbena so its not such a bad mistake.
It could be one I sprayed recently which could explain the sad look... the Salvia is a perennial and has a very strong taproot which makes it close to impossible to pull out. My only option is to spray, digging out would disturb soil to much and more weeds would be the result in this highly disturbed area. i observed a lot of weed (Salvia, Cape, Buchan, Spear thistle, sow thistle ... ) germination as a result of several arson fires lit further east of your record ...