Some consider it means the flower that grows on the banks of the river Lis, which separated France and Artois from Flanders.

Turning to the literature of the past, Shakespeare has several allusions to the plant, as in "I Henry VI," where a messenger enters and exclaims:-- "Awake, awake, English nobility! Let not sloth dim your honours new begot; Cropp'd are the flower-de-luces in your arms; Of England's coat one half is cut away." Spenser mentions the plant, and distinguishes it from the lily:-- "Show mee the grounde with daifadown-dillies, And cowslips, and kingcups, and loved lillies; The pretty pawnee, And the cherisaunce, Shall march with the fayre flowre delice." Another instance is the mignonette of our French neighbours, known also as the "love-flower." One of the names of the deadly nightshade is belladonna which reminds us of its Italian appellation, and "several of our commonest plant names are obtained from the Low German or Dutch, as, for instance, buckwheat (_Polygonum fagopyrum_), from the Dutch _bockweit_." The rowan-tree (_Pyrus aucuparia_) comes from the Danish _roeun_, Swedish _ruenn_, which, as Dr.Prior remarks, is traceable to the "old Norse _runa_, a charm, from its being supposed to have power to avert evil." Similarly, the adder's tongue (_Ophioglossum vulgatum_) is said to be from the Dutch _adder-stong_, and the word hawthorn is found in the various German dialects.
As the authors of "English Plant Names" remark (Intr.

xv.), many north-country names are derived from Swedish and Danish sources, an interesting example occurring in the word _kemps_, a name applied to the black heads of the ribwort plantain (_Plantago lanceolata_).

The origin of this name is to be found in the Danish _kaempe_, a warrior, and the reason for its being so called is to be found in the game which children in most parts of the kingdom play with the flower-stalks of the plantain, by endeavouring to knock off the heads of each other's mimic weapons.

Again, as Mr.Friend points out, the birch would take us back to the primeval forests of India, and among the multitudinous instances of names traceable to far-off countries may be mentioned the lilac and tulip from Persia, the latter being derived from _thoulyban_, the word used in Persia for a turban.