Kingdom: Plantae
Division: Magnoliophyta
Class: Eudicotyledoneae
Subclass: Rosidae
(Unranked): Eurosids
Order: Oxalidales
Family: Oxalidaceae
Genus: Oxalis
Species: Oxalis crassipes
Common name: White wood sorrel

The genus Oxalis is annual or perennial. The leaves are divided into three to ten or more obovate and top notched leaflets, arranged palmately with all the leaflets of roughly equal size. The majority of species have three leaflets; in these species, the leaves are superficially similar to those of some clovers. Some species exhibit rapid changes in leaf angle in response to temporarily high light intensity to decrease photoinhibition. The flowers have five petals, which are usually fused at the base, and ten stamens. The petal colour varies from white to pink, red or yellow; anthocyanins and xanthophylls may be present or absent but are generally not both present together in significant quantities, meaning that few wood-sorrels have bright orange flowers. The fruit is a small capsule containing several seeds. The roots are often tuberous and succulent, and several species also reproduce vegetatively by the production of bulbils, which detach to produce new plants.
Oxalis spreads prolifically and is a real challenge to eradicate. The main problem is that you can pull out the weed but one leaves under the soil its parent bulb with a number of little bulblets attached to it.

Oxalis crassipes 'Alba'Oxalis crassipes Alba Oxalidaceae .JPG

Thanks to Wikipedia for text and information:

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