The Collaborative International Dictionary of English v.0.48:
Sorrel \Sor"rel\, n. [F. surelle, fr. sur sour, fr. OHG. s?r
sour. See Sour.] (Bot.)
One of various plants having a sour juice; especially, a
plant of the genus Rumex, as Rumex Acetosa, Rumex
Acetosella, etc.
[1913 Webster]
Mountain sorrel. (Bot.) See under Mountain.
Red sorrel. (Bot.)
(a) A malvaceous plant (Hibiscus Sabdariffa) whose acid
calyxes and capsules are used in the West Indies for
making tarts and acid drinks.
(b) A troublesome weed (Rumex Acetosella), also called
sheep sorrel.
Salt of sorrel (Chem.), binoxalate of potassa; -- so called
because obtained from the juice of Rumex Acetosella, or
Rumex Axetosa.
Sorrel tree (Bot.), a small ericaceous tree (Oxydendrum
arboreum) whose leaves resemble those of the peach and
have a sour taste. It is common along the Alleghanies.
Called also sourwood.
Wood sorrel (Bot.), any plant of the genus Oxalis.
[1913 Webster]