Apium graveolens var. secalinum

Leaf celery (Apium graveolens Secalinum Group or Apium graveolens var. secalinum), also called Chinese celery or Nan Ling celery, is a group of cultivars of Apium graveolens cultivated in East Asian countries for their edible, flavorful stalks and leaves. The stems are thinner than those of Western celery, and curved into round, hollow stalks. Also, unlike with Western celery, the leaves are used as well as the stalks. It has a stronger taste and smell compared to celery. It is used as a flavoring in soups and sometimes pickled as a side dish....read more on Wikipedia.