Manna of various sorts is collected from many different kinds of plant; that which supported the Israelites in the desert is supposed to have been an exudation from the tamarisk; but Sicilian manna is the only kind that is recognised as an article of European trade. In Sicily the manna ash is planted in _frassinetti_ or ash-yards, grown for eight years and regularly tapped, till the main stem is exhausted, when it is cut down, and a fresh growth is allowed to spring from the root. The active principle in manna is mannite, a hexatomic alcohol, chemically expressed as C_{ 6}H_{ 8}(OH)_{ 6}. The manna ash is not often seen in this country; those specimens which are of any size are invariably grafted plants; but a stock is easily raised from seed, which Continental nurserymen readily supply. In Dalmatia and Montenegro, where this tree abounds, drivers stick the flowers thereof in the harness of their horses to keep off flies, which dislike the peculiar odour. A Chinese species (_F. mariesii_) is near of kin to _F. ornus_, and is said to bear flowers of superior beauty to that tree; but of this I can only write from hearsay.
When we speak of a lime tree we conform to a corrupt usage, for the right English name is "line" or "linden tree," linden being the adjectival form of the Anglo-Saxon "lind," just as "asp" and "oak" give the adjectives "aspen" and "oaken." The late Professor Skeat, foremost authority in English etymology, observed that "the change from 'line' to 'lime' does not seem to be older than about A.D. 1700"; but he overlooked the use of the modern form by John Evelyn, who, in his _Sylva_ (1664), writes always of "the lime tree or linden," showing that the change had taken place between his day and Shakespeare's.
_Prospero._ ... Say, my spirit, How fares the King and his?
_Ariel._ Confin'd together In the same fashion as you gave in charge; Just as you left them, sir; all prisoners In the line grove which weather-fends your cell. (_Tempest_, Act v. sc. 1.)
The root meaning of the word is "smooth," referring to the texture of the timber, which caused it of old to be in great request for making shields, so that in Anglo-Saxon _lind_ meant a shield, as well as being the name of the tree.