Is it a football? No, it's an enormous Cypriot lemon

A lot of discussion is given to strange cultures and freakish monsters. Even exiting new weapons, religions, and magics, or even planes of reality.
What about plants? They usually don’t get much attention unless they are a serious threat to a party of adventurers. What kind of subtle, atmospheric contributions could unusual plants make to a campaign? Consider this:

• Normal plants of unusual size
• Normal vegetables of extraordinary flavor
• Moonflowers (They blossom at night and turn to face the moon)
• Rapidly growing grass that provides sustenance for an entire village.
• Abnormal-sized citrus that “carbonate” the juice, producing something similar to Orange Crush
• Especially potent sugarcane which sweetens the fruit of surrounding trees.
• Tropical trees with unusually large and tough leaves, which function similar to leather.
• Bright orange flowers with dry leaves that actually use flash fires to pollinate.
• WereTrees that loose all their leaves each full moon.
• Trees that grow a translucent, fireproof bark, serving as protection from the elements, but allowing sunlight through
• Squash that grows in a symbiotic relationship with local brownies
• Tarfruit that burns brightly for an hour.
• Weeds that are impossible to kill (oh, wait, that one is not speculative!)
• A colossal dandelion with floating seeds that, in a strong wind, create a field of caltrop-sized barbs.
• Pineapples with unusually acidic juice
• etc.