Is this for the Daily telegraph crossword by anychance? The answer is rhizzoid.
lichen
Symbiosis
Lichen is the base in the chain of succession. It starts at lichen, the moves on to moss, then to small plants, and so on.
lichen
lichen and other sea plants
Moss. lichen
Offspring which arise as a contiguous outgrowth of the parent is called budding. The process of a parent cell dividing into a large number of genetically identical cells all at once is known as multiple fission.
lichen
lichen
Lichen is a mixture of algae / cyanobacteria and fungi. Lichens may look like plants but they do not reproduce with flowers. Lichens do not have roots like plants. They grow on plants as a substrate not as a parasite.
plants, grasses, moss, and lichen
Musk ox and lichen