Lysigenous

Lysigenous is an anatomical term used in botany to describe tissues or spaces produced by the lysis, or dissolution, of cells. The word is derived from Greek lysis (to loosen or dissolve) and -genous (produced by). In plants, lysigenous describes the formation of aerenchyma—air-filled channels in roots or stems that develop when certain cortical cells die and their contents are degraded, leaving interconnected air spaces. This contrasts with schizogenous aerenchyma, formed by the separation of living cells without cell rupture.

Lysigenous aerenchyma commonly forms under hypoxic or waterlogged conditions and is often associated with ethylene signaling and programmed cell death. It is widespread among flood-adapted species, including many wetland grasses and dicots; rice (Oryza sativa) is a well-known example. The resulting air spaces facilitate diffusion of gases to subterranean tissues, improving root respiration and survival in flooded soils.

In broader usage, lysigenous can describe any tissue or structure produced by lysis of cells, though in plant anatomy the term is most frequently linked to aerenchyma formation. The term helps distinguish processes that involve cell rupture from those that form spaces by cell separation alone.