The wood sorrel is in the genus Oxalis. There is about 850 species in this group. The roots can be in the form of bulbs, rhizomes, or tubers. Shamrocks and wood sorrels are both in this group. True shamrocks include white clover, red clover, and black medic. With that said, one type of wood sorrel is often sold under the name "Shamrock" and is not considered a shamrock or clover.
The wood sorrel, shamrock, has pink flowers. Each flower has five petals and ten stamens. When it is ready to reproduce, the seeds are tossed away from the mother plant. At night both the flower blooms and leaves close. There are three leaves per stem that look clover like. They have a sour taste because they contain oxalic acid. The acid sap that the wood sorrel produces protects the plant from slugs. Moles also leave the shamrock alone. The root of this wood sorrel is a rhizome.
Shamrocks make wonderful border flowers. The leaves create a soft rounded mound and the small pink flowers hover over the foliage in abundance. The shamrock blooms from spring through fall. They are about eight to ten inches tall, and will grow in full sun or partial shade. These carefree flowers look especially nice along walkways, driveways, next to buildings, or the outer edge of flowerbeds.