Mushroom
2 of the 6 encyclopedias on this shelf carry an entry for Mushroom. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a popular name for a large number of the higher fungi. There are several hundred species. They may be designated in general as flowerless plants, consisting of a stem, surmounted by a cap-shaped structure frequently like that of a parasol. The word is French. The corresponding English word is toadstool. Mushrooms are found in almost all parts of the world. They grow in a great variety of situations, varying from a dark wood to the edge of a sunny sidewalk, and from a compost heap to the shelter of a rock pile. It may be said in general, however, that mushrooms require moisture and decaying vegetable matter for their growth. Young mushrooms are usually white in color. They grow rapidly, giving rise to the popular expression "mushroom growth." An examination of the under surface of the cap shows that it is composed of thin blades or gills, shaped like a knife blade. At maturity the surface of the gills produces a fine powder known as spores, from which new plants may be produced. Ordinarily, however, mushrooms are propagated by slender threads, called spawn, produced in the soil around the base of an old plant. Certain species have been cultivated for food for centuries. The industry originated, very possibly, in France. They are raised very successfully in cellars and caves, not because they grow better in the dark, but because these places have a more uniform temperature. Growers claim that it is impossible to raise mushrooms by rule. Of two beds planted side by side under apparently exactly similar conditions, one yields an abundance of mushrooms; the other is a total failure. A writer in Bailey's Cyclopedia speaks of succeeding well with a soap box thrust under the bed. In the United States and Canada edible mushrooms grow abundantly in fields and pastures, particularly around stumps. The demand is so great, however, that artificial mushroom raising has become an important industry. They are served like green peas with meat, or made into catsup. They are also canned, like vegetables, and may be had at all seasons of the year. As the poisonous species can be told only with great difficulty from those which are edible, it is needless, perhaps, to say that the uninformed should proceed with the utmost caution, that is to say, let mushrooms alone. See Truffles
Collier's New Encyclopedia (1921)
or AGARIC, a genus of fungi, of the sub-order Hymenomycetes, having a hymenium of unequal plates or gills on the lower side of the pileus. The species are very numerous. Many are poisonous, many are edible, and some are among the most esteemed fungi.
What Has Changed in the Last Century
Aiton's 1910 entry calls mushrooms "flowerless plants," and Collier's in 1921 files them as a genus of fungi among the plants. That classification is gone: Robert Whittaker's 1969 five-kingdom scheme gave Fungi a kingdom of their own, and molecular work since the 1990s has shown fungi are more closely related to animals than to plants. The old lumped genus Agaric has likewise been broken up into hundreds of genera, while cultivation, which Aiton said "it is impossible to raise by rule," is now a controlled industry built on sterilised grain spawn, with China producing the great majority of the world's mushrooms. The warning still holds, though: telling a deadly Amanita from an edible species remains a job for someone who knows what they are looking at.
Written for this edition, 2026.