Acacia
2 of the 6 encyclopedias on this shelf carry an entry for Acacia. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a-ka'sha, a genus of shrubs and trees belonging to the pea family. There are between four and five hundred species. The acacia is a native of every continent except Europe; but it has been introduced into England and southern Europe from Africa and from Australia. The North American locust is closely related to the acacias, as are also the mimosae, or sensitive plants, the lupines, sennas, and laburnums, as well as all the varieties included under the general name leguminosae, or pod-bearing plants. In some species the twice-pinnate leaves are reduced to mere rudiments, and the leaf stalk is broad and flat, with one edge toward the sun. Several kinds yield the gum arabic and gum senegal of commerce. The bark and pods of one or more kinds are used for tanning leather. The seeds of one species are used for soap. Catechu, an astringent extract much used by the tanner, and in medicine as a remedy for diarrhoea and dysentery, is obtained from a species found in India. Florists list over fifty acacias as desirable conservatory plants. Some kinds yield valuable and lasting lumber. One species is thought to be the shittim-wood of the Bible. See Locust ; Mimosa; Leguminosae
Collier's New Encyclopedia (1921)
a genus of plants belonging to the mimosa, one of the leading divisions of the great leguminous order of plants. They abound in Australia, in India, in Africa, tropical America and generally in the hotter regions of the world. Nearly 300 species are known from Australia alone. They are easily cultivated in greenhouses, where they flower, for the most part, in winter or early spring. The type is perhaps the Acacia Arabica, or gum arabic tree, common in India and Arabia. It looks very beautiful with its graceful, doubly pinnate leaves and its heads of flowers like little velvety pellets, of bright gamboge hue. Other species than the A. Arabica produce gum arabic. That of the shops is mostly derived from the A. vera, a stunted species growing in the Atlas mountains and other parts of Africa. a name given to a
What Has Changed in the Last Century
Both entries treat Acacia as one worldwide genus, with Aiton's counting "between four and five hundred species" and Collier's naming Acacia arabica as the type. That single genus no longer exists: after a bitterly contested decision confirmed at the 2011 International Botanical Congress in Melbourne, the name Acacia was kept for the roughly 1,000 Australian wattles, while the African and Asian species were moved into Vachellia and Senegalia. Collier's gum arabic tree is now Vachellia nilotica, and most commercial gum arabic — still overwhelmingly a Sudanese export — comes from Senegalia senegal. Aiton's flattened leaf stalk "with one edge toward the sun" is the structure botanists call a phyllode, and Central American bullhorn acacias have since become a textbook case of mutualism after Daniel Janzen's 1966 work on their resident ants.
Written for this edition, 2026.