Selected shallow water marginals

Sweet Flag (Acorus calamus)
This is an attractive old favourite that is available either in green (wild type) or variegated for (Acorus calamus 'Variegatus'), the latter being more popular than the former. Although the leaves are Iris-like in appearance, the flowers could not be more different. The most charitable thing that could be said of Sweet or Myrtle Flag inflorescences is that they are far from spectacular. The narrow, pointed leaves give off an interesting citrus-like smell when cut or damaged, and young leaves, particularly in the spring, have a rosy tinge that disappears as they grow.

Water Plantain (Alisma spp)
Of the two species that are generally available, the more popular one is Alisma platago-aquatica (Water Plantain or Great Water Plantain), which has considerably wider leaves than those of A. lanceolatum. These plants are grown primarily for their foliage, rather than their wiry inflorescences of small whitish flowers, which can look a little untidy once flowering is fully under way. Alismas are hardy species that see freely and can therefore become invasive

Deep-water marginals

Pickerel Weed (Pontederia cordata)
This is a vigorous plant that dears narrowly heart-shaped leathery leaves. Pickerel weed does well in a range of conditions. While being quite hardy when planted in deep water, plants that are cultivated in moist soil or very shallow water should be given some winter protection in ice-prone regions to prevent their roots from freezing.

In addition to the widely available wild type, a few colour varieties have also begun to appear more regularly in recent years, including white, pink and deep mauve forms. A second taller species, P. lanceolata, which has narrower leaves than P. cordata, is also occasionally available.

Arum Lily (Zantedeschia aethiopica)
The Arum Lily is traditionally grown as a normal garden plant in frost-free areas. Some varieties are frost-hardy in temperate zones that do not experience severe winters. In ponds, three varieties are most commonly encountered: the "original" White Arum Lily, the shorter and reportedly tougher, but also white, Z.aethiopica 'Crowborough' and the unusual 'Green Goddess', whose 'petals' (actually a spathe, which is a modified leaf) are mainly green around the edges and creamy white  towards the centre, from which the yellow flower spike (spadix) emerges. In addition, the tenderer Z. elliotana, with gorgeous yellow spathes and cream-speckled dark green leaves, is occasionally available. All are striking.