Trifolium pratense

The scientific name for the weed Red Clover.
Trifolium repens

The scientific name for the weed White Clover.
Troublesome Trio

A term used (Martin A.F. Sutton, (1962), Lawns and Sports Grounds, pp.105-109) to describe major weeds of fine turf surfaces: White Clover, Pearlwort and Yarrow. Other clovers and trefoils: Suckling Clover (Trifolium dubium), Black Medick (Trifolium dubium) and Birdsfoot Trefoil (Lotus corniculatus) are sometimes grouped under the Clover heading. The main three troublesome trio weeds are difficult to control, requiring a continued and planned effort over a long period of time.
Veronica chamaedrys

The scientific name for the weed Germander Speedwell.
Veronica filiformis

The scientific name for the weed Slender Speedwell.
Veronica persica

The scientific name for the weed Common Field Speedwell.
Veronica serpyllifolia

The scientific name for the weed Thyme Leaved Speedwell.
Vicia sativa

The scientific name for the weed Common Vetch.
Wall Speedwell

An annual weed of lesser maintained and neglected turf surfaces. Its scientific name is Veronica arvensis. The main flowering period is March to October, with small blue flowers. It has preference for dry soils, without shade.
Weed

An undesirable plant. Sometimes the wording ‘growing in an unwanted place' is added to a definition, but this doesn't really add any extra value to the meaning, because it is still undesirable at the end of the day. Weeds can be categorised as Broad-Leaved Weeds and Small-Leaved Weeds.