In a mossy vale not far from Montpelier, Dave Kaczynski holds a small yellow mushroom. “These never came to bear here this year,” he says. It hasn’t rained in days; the forest floor is dry, and the ...

Yellow parasol mushroom sclerotia growing on dead orchid roots and bark (left) and young mushrooms (right). Scot Nelson (right) Q: I repotted some houseplants a few months ago and now I see small, ...