Modular growth in verticillate podetia of Cladonia

Abstract

Verticillate proliferations are characteristic of the podetia in certain species of Cladonia section Cladonia that have been informally classified in the Cladonia cervicornis group. The proliferations form at the center of the closed scyphus and they usually give rise to further tiers of central proliferations. They are initially formed from meristematic tissue that persists in the upper layer of the scyphus, which becomes surrounded by nonmeristematic tissue during widening of the scyphus. Once the supporting scyphus attains a certain width, this meristematic tissue becomes active, producing a vertical proliferation. The proliferation, which starts as an indistinct mass of fungal tissue, later becomes lichenized and differentiates into a characteristic podetial morphology that includes a stipe and scyphus. The vertical proliferation represents a new module of the podetium.

Key Words:

• lichen morphology
• meristems
• systematics