Answer:

moss

Answer	Crossword Clue
MOSS	Iceland or club
MOSS	Damp growth
MOSS	Spanish or Irish

MOSS	What certain stones don't gather
MOSS	You won't find it on a rolling stone
MOSS	Shade of green
MOSS	It grows on trees
MOSS	Primitive vegetation
MOSS	Bryophyte
MOSS	Sign of stagnation
MOSS	Lycopodium, e.g.

MOSS	Bryologist's topic
MOSS	Rolling stone's lack
MOSS	Tree-trunk growth
MOSS	Welcome growth in Japanese gardens
MOSS	Trunk attachment
MOSS	Forest growth
MOSS	Wet ground growth
MOSS	Trunk growth

MOSS	Damp area growth
MOSS	Some spores, all grown up
MOSS	Low-growing greenery
MOSS	Playwright Hart
MOSS	Shady growth
MOSS	Tree trunk greenery
MOSS	Matted growth
MOSS	What rolling stones don't gather

MOSS	Forest-floor plant
MOSS	Tree trunk growth
MOSS	Common tundra vegetation
MOSS	Forest floor growth
MOSS	Proverbial ground cover
MOSS	Rolling stone's lack, proverbially
MOSS	Plant that can grow on trees
MOSS	Sphagnum or peat

MOSS	Green growth
MOSS	It doesn't gather on rolling stones
MOSS	Moor growth
MOSS	Terrarium greenery
MOSS	Kate on the runway