Salicylaldehyde be prepared from the corresponding phenol by the Duff reaction, or by treatment with paraformaldehyde in the presence of magnesium chloride and a base. Salicylaldehyde was identified as a characteristic aroma component of buckwheat. It is also one of the components of castoreum, the exudate from the castor sacs of the mature North American beaver ("Castor canadensis") and the European beaver ("Castor fiber"), used in perfumery. Furthermore, salicylaldehyde occurs in the larval defensive secretions of several leaf beetle species that belong the subtribe Chrysomelina. An example for a leaf beetle species that produces salicylaldehyde is the red poplar leaf beetle
Castor and Pollux branches. The standard Spartan oath was to swear "by the two gods" (in Doric Greek: νά τώ θεὼ, "ná tō theō", in the Dual number). The rite of "theoxenia" (θεοξενία), "god-entertaining", was particularly associated with Castor and Pollux. The two deities were summoned to a table laid with food, whether at individuals' own homes or in the public hearths or equivalent places controlled by states. They are sometimes shown arriving at a gallop over a food-laden table. Although such "table offerings" were a fairly common feature of Greek cult rituals, they were normally made in the shrines of the gods