trefoil [O.Fr.,=three-leaf], in botany, name for several plants, chiefly of the pulse family, having trifoliate leaves. Best known of the trefoils is clover. The bird's-foot trefoil (Lotus corniculatus) is an Old World forage plant and weed that has been naturalized in North America; the prairie trefoil (L. americanus) is a related native American plant. The shrubby trefoil is the hop tree. Tick trefoil is a name for the tickseed, or beggarweed.

Perennial, spreading, herbaceous legume (Lotus corniculatus) native to Europe and Asia but introduced to other regions. The stem grows to about 2 ft (60 cm) long. Its leaves consist of three oval leaflets, broadest near the tip. The yellow flowers (sometimes tinged with red) grow in clusters of 5 to 10. Often used as forage for cattle, it is occasionally a troublesome weed.

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Trefoil (from Latin trifolium, "three-leaved plant", French trèfle, German Dreiblatt and Dreiblattbogen) is a graphic form composed of the outline of three overlapping rings used in architecture and Christian symbolism. The term is also applied to other symbols of three-fold shape.

Architecture

Trefoil is a term in Gothic architecture given to the ornamental foliation or cusping introduced in the heads of window-lights, tracery, panellings, etc., in which the center takes the form of a three-lobed leaf (formed from three partially-overlapping circles). One of the earliest examples is in the plate tracery at Winchester (1222 - 1235). The fourfold version of an architectural trefoil is a quatrefoil.

A trefoil combined with an equilateral triangle was also a moderately common symbol of the Christian Trinity during the late Middle Ages in some parts of Europe. Two forms of this are shown below:

A dove, symbolic of the Holy Spirit, is sometimes depicted within the outlined form of the trefoil combined with a triangle.

Heraldry

The heraldic trefoil is a stylized clover.
It should not be confused with the figure named in French heraldry tiercefeuille, which is a stylized flower with three petals. It differs from the heraldic trefoil in being not slipped. It could be translated as threefoil.

Symbols

• The symbol for recycling (see Recycling symbol).
• The symbol indicating radioactivity.
• One particular stylized form of the heraldic trefoil is used as the main element in the logo of most Girl Guide and Girl Scout organizations and is one of the more popular Girl Scout Cookies.
• The logo of Adidas.

Trademark

The green trefoil is registered under international trade-mark conventions as a symbol of Ireland. Shamrocks do not appear on Irish coins, bank-notes or postage stamps, as a rule.

Other meanings

• A trefoil formation is a cross-sectional arrangement of electrical cables that minimises electrodynamic forces during fault conditions.

See also

• Quatrefoil
• Trefoil knot

External links

• Explanation of Christian symbolism of Trefoil

References