Sheep's sorrel currently has a botanical name of Rumex acetosella though at times it has been known as Acetosa acetosella. It has a creeping root system, which is very similar to a rhizome system.
Interestingly, the green leaves are also edible and can be used in salads. For those of you who grow the edible-leaved hibiscus acetosella, these leaves are also perfect for a salad and taste similar ...