Bioluminescent Mushroom Greenhouse in an Abandoned Subway Tunnel

A towering sentient mushroom with bioluminescent spores and ancient tree roots for feet, floating autumn leaves , in inside a vast abandoned subway tunnel transformed into an underground greenhouse sanctuary, Art Nouveau stained glass window design with flowing organic lines, rich emerald greens and deep amber oranges with phosphorescent white accents, mystical harmony blended with gentle melancholy for forgotten places,

Prompt breakdown