Clover (Trifolium spp.) is a member of the pea family and is related to many popular perennial flowers, including lupins and sweet peas. The botanical name Trifolium means three-part leaves, which describes the plants' foliage perfectly. Each leaf has three leaflets, either lance- or heart-shaped, depending on the type of clover. There's often a crescent or arrowhead marking on the leaves. Several ornamental perennials have similar leaves.
A vigorous perennial with lance-shaped leaves, fleecesflower (Persicaria microcephala) is also known as smartweed and knotgrass. The leaves have distinctive arrowhead markings that are more intensely coloured in hot weather. This perennial is grown for the foliage, since the flowers are insignificant. Fleeceflower makes a mound 2 feet tall and half again as wide and grows well in sun or shade. The cultivar Red Dragon has burgundy leaves with silvery markings and combines well with silver-foliaged plants such as Artemesia and lamb's-ears (Stachys byzantina).
If your mental picture of clover includes heart-shaped leaves, check out oxalis (Oxalis debilis), an old-fashioned charmer. This tidy plant makes rounded clumps of clover-like leaves topped with pink or white flowers. While it's origins in South America and southern Africa suggest this is a hot-climate plant, Oxalis, also known as wood sorrel, is hardy enough to grow in the UK. Grow oxalis in sun or partial shade, where it will bloom in spring and again when the weather cools in the autumn.
The Royal Horticultural Society classifies baptisia (Baptisia australis) as "very hardy." The plant is also known as blue false indigo and wild indigo. It is a shrubby perennial with blue flowers and clean, clover-like foliage. This American native grows 3 to 4 feet high and wide. Baptisia can be slow to establish, but once it does, it's trouble-free, rarely bothered by insects or disease. It forms pea-podlike seed heads in the fall, which, if left on the plant over winter, rattle in the slightest breeze.
Clover as a ground cover
White or Dutch clover (T. repens) was once added to grass seed mixtures because it fixes nitrogen into the soil, feeding the grass roots. It still makes a good ground cover for areas where grass won't thrive, covering bare soil quickly with a soft green carpet. Clover looks its best when mowed regularly. The flowers do attract bees, so use it with caution near areas where children play.