Unlike the other weeds I’ve examined to date, this one is a perennial. It also is apparently difficult to control with herbicides, not that I like to go that route. So the best approach to controlling it seems to be to dig it up, taproot, rhizomes, and all, and mulch heavily after digging to prevent seeds from germinating.
Growing up, we called almost anything with a three-part (tripartite–another Scrabble word) leaf a “clover.” But clover is a different plant from wood sorrel. How to tell the difference?
Oxalis leaves are heart or spade-shaped and partly folded. Their leaf margins are smooth. Clovers, on the other hand, have oval-shaped leaves with finely serrated margins and prominent veins. Oxalis species have five-petaled yellow flowers at maturity.
Oxalis corniculata, or creeping woodsorrel, is a related perennial weed that grows low to the ground and roots where it establishes ground contact. Its leaves, shaped like other Oxalis species, fold downward in intense sunlight. When removing this weed, take care to dig the whole plant. If portions of the taproot or stolons are left in the ground, the plant can quickly reestablish.