A corm is a modified plant stem some plants use as a storage organ or for hibernation.  Corms are structurally plant stems, and can produce roots. On the top of the corm, one or a few buds grow into shoots that produce normal leaves and flowers.
Some plants with corms regularly replace their older corms with a stack of younger ones. In other species their corms simply grow larger in most seasons. Yet others split when multiple buds or stolons on a large corm sprout independently.
Plants that form corms include the following species:
- Sagittaria spp. (arrowhead or wapatoo)
- Eleocharis dulcis (Chinese water chestnut)