cephalodium

cephalodium (plural cephalodia)

1. A small gall-like structure found in some lichens that contain cyanobacterial symbionts.
   • 1947, Ivan Mackenzie Lamb, A monograph of the lichen genus Placopsis Nyl, page 166:

     The Nostocoid type consists of small rounded blue-green cells not over 5p. in diameter and arranged in chains which are often much broken up in the cephalodium, so that the concatenate arrangement is hardly apparent.

• cephalodial

• cephalolichen