From Chapter XIV of Etidorhpa, see attached pic:
But toadstools are foul elements of low organization. They are neither
animals nor true vegetables, but occupy a station below that of plants
proper," I said.
" You are acquainted with this order of vegetation under the most
unfavorable conditions; out of their native elements these plants degenerate
and become then abnormal , often evolving into the poisonous earth fungi
known to your woods and fields. Here they grow to perfection. This is their
chosen habitat. They absorb from a pure atmosphere the combined foods of
plants and animals, and during their existence meet no scorching sunrise.
They flourish in a region of perfect tranquility, and without a tremor,
without experiencing the change of a fraction of a degree of temperature,
exist for ages. Many of these specimens are probably thousands of years old,
and are still growing; why should they ever die? They have never been
disturbed by a breath of moving air, and, balanced exactly on their
succulent, pedestal-like stems, surrounded by an atmosphere of dead
nitrogen, vapor, and other gases, with their roots imbedded in carbonates
and minerals, they have food at command, nutrition inexhaustible."
" Still, I do not see why they grow to such mammoth proportions."