This perennial is semi-evergreen so it can lose some of its leaves in winter. In colder regions or more exposed gardens, it may lose them all, but then fresh new growth appears again in spring.

• Position: full sun or partial shade
• Soil: moist to wet or boggy, humus-rich soil or aquatic compost
• Depth of water: 0-5cm
• Rate of growth: fast-growing
• Flowering period: June to August
• Hardiness: frost hardy (may need winter protection)
  
  As dwarf, marginal or aquatic perennials go, this oar leaved arrowhead takes some beating. The lance-shaped leaves are set against whorls of 3-petalled white flowers, each with conspicuous central green 'buttons', opening to a boss of yellow stamens. It's perfect for bog gardens, container water gardening and smaller ponds - or it can be grown as an oxygenator if partially submerged.
  
  
• Garden care: To prevent this plant spreading too vigorously, it is advisable to pot it up (using aquatic compost) into a pond basket. Then, lift and divide the plant as necessary. In late winter, pop on a pair of tough gloves, and comb through the plant in late winter to remove any dead foliage.