The text reads:
Herba Parietis or the Wall Flower
As it Grew out of the Stone Chamber
Belonging to the
Priſon of London Called
Being A History
Wch is Partly True
Wherby A Marriag
Betweene Reallity &
fancie is Solemnised
Written By: I: B: whilst he was A Prisoner therr.
Every time I start browsing the British Library collections online, I find lots of stuff I want to post. This is from George III’s collection of geographical material, so I guess it must be C18th. I’ve slightly reduced the size; you can see it full-sized here.