Arnhem, called Arnoldi Villa in the middle ages, is, according to some, the Arenacum of the Romans, and is first mentioned in a document in 893.
In the genus Sequoia there may be as many as sixty archegonia (Arnoldi and Lawson) in one megaspore; these occur either separately or in some parts of the prothallus they may form groups as in the Cupressineae; they are scattered through the prothallus instead of being confined to the apical region as in the majority of conifers.
Rafflesia arnoldi, which is found only in certain parts of Sumatra, is the largest flower in the world.