Oxygenating Plants


Peltandra or Arrow Arum

A hardy, semi-evergreen perennial originally from North America, this is a plant highly regarded for its form and structure — considered by many to be architecturally significant in the garden. Individual plants are not particularly big, but a large group can be stunning. For this reason, Peltandra is best suited to larger ponds.

The leaves are bright green, shiny, strongly veined and, most significantly of all, are arrow-shaped. Sometimes the undersides of the leaves take on a chestnut hue. When grown in deeper water, they tend to be evergreen.

Tiny greenish flowers on a short spike enclosed by a conspicuous greenish white spathe appear in early summer. Green berries follow.

Set plants out, around 30cm (12in) apart, during spring. The ideal water depth is 0-25cm (0—10in). Choose a position in full sun or very light shade. It is best to plant directly into the soil, as Peltandra does not take kindly to container growing. Remove any faded foliage in late autumn. In winter, protect plants not under water by packing straw or bracken around the crowns.

To propagate, divide the creeping rhizomes in spring.

This plant may also be found under its old names of Peltandra undulata or P sagittifolia. Sometimes the white arrow arum (P sagittifolia or sometimes seen as P. alba) has flowers of a purer white, with red autumn berries. P virginica often turns evergreen in deep water.

Ranunculus or Spearwort

Most species in this genus are relatively invasive —think of buttercups in the lawn, for example. Ranunculus lingua is no different and will happily extend its creeping roots and colonize a large area. It is, therefore, not really suitable for the small pond. It redeems itself in that it is a marginal with lovely showy flowers.

The blooms are large, some 5cm (2in) across, golden yellow and have a sheen to them that glistens in the sun. They appear from mid-spring to early autumn. Pollinated flowers produce pretty, light green, mace-like seed heads that ripen slowly, turning to light brown.

Long, spear-shaped leaves — hence the common name — are bright green for most of the season, but are decidedly pinkish when young.

Ranunculus aquatilis is a spreading, invasive species whose flowers and stems are often submerged under-water. The lesser spearwort (R. flammula) is less invasive, lower-growing, and also less decorative. This form can be chosen for a small pond.

Grow marginal ranunculus in full sun or light shade, and plant them during the spring either directly into the soil or into planting baskets for siting on ledges around the pond margins.

Remove all old, dying or dead leaves and stems in autumn to avoid polluting the water. Should stems break and fall into the water, they will most probably produce roots from the leaf nodes — another way for the plant to spread.

Divide overgrown clumps, probably every three to four years, in spring.

To propagate, either divide as suggested, or sow seeds in to pots of moist compost in spring, and keep them in a shaded cold frame.

Sagittaria or Japanese Arrowhead

All sagittarias, originally from various parts of the Far East and northern Europe, are popular and attractive, even regarded by some as architectural in form.

The most often seen form is Sagittaria sagittifolia.

Leaves of Sagittaria sagittifolia (Alismatacea...

Leaves of Sagittaria sagittifolia (Alismataceae). Deutsch: Luftblätter ("gemäßigte Form") des Pfeilkrautes (Sagittaria sagittifolia); hier bei Gegenlicht von unten. (Photo credit: Wikipedia)

The old botanical name for Sagittaria sagittifolia is S. japonica, and it may still be found under this name in nurseries. Its leaves are distinctive, particularly when combined with the flowers on the double form.

From mid- to late summer fairly large spikes of white flowers with black and red centres are produced. The male flowers are at the tops of the spikes and females below.

Elegant arrow-shaped leaves are held above the water, while long ribbons of leaves are produced under water.

The form S. latifolia is similar but less hardy, while S. sagittifolia ‘Flore Pleno’ produces double flowers.

When growing more than one plant, set them out 23cm (9in) apart. Plant tubers or young plants directly into the soil or simply weigh them down and drop them into the water at the pond’s edge. The preferred water depth for this plant is 5-30cm (2-12in); the deeper the water, the fewer the flowers. Cut back all growth in the autumn. If practicable, feed the plants in spring.

The easiest way to propagate them is to divide them every second or third year, when they get overcrowded. Do this in spring. Also, seeds can be sown under glass in spring.

This plant has edible roots. It is sometimes referred to as the duck potato because, in large duckponds, the feathery inhabitants will attack and eat the tubers.

Typha Reed Mace

This is a tall plant. The sword-shaped, blue-green leaves can reach considerable heights, and throughout summer they frame the taller brown-tipped flower stems or ‘pokers’. The leaves die back in winter but the woody flower stem remains throughout the winter, looking quite attractive when covered with frost.

This is not a plant for the small — or even lined — pond as it possesses a very strong and vigorous system of pointed roots. These roots are quite capable of penetrating most flexible liners! The plant is therefore best suited to large, natural ponds and lakes. It has been successfully used in aiding the stabilization of riverbanks, as the massive root systems form a tough, dense, almost raft-like mat just below the surface.

Typha angustifolia (slender reed mace) is a graceful plant, slightly shorter in height, but otherwise similar.

On the other hand T. minima (miniature reed mace) is a useful plant for small ponds. Its round seed head is considerably different from the cigar-shaped heads of the other two, and the leaves are narrower. The main similarity it has with the others is its tendency to produce pointed roots.

Placing an additional layer of liner between the root system and the pond liner will certainly protect the liner, but it is a great deal of effort for a plant that is not, it must honestly be said, the most decorative of marginals! Old foliage should be cut away during late autumn, otherwise it will die and fall into the water, polluting it. Typhas do not require feeding at any time.

To propagate, just remove a length of root system that has healthy tips and roots, pot it into a heavy loam or clay soil, and place it in the water.

Veronica Beccabunga or Brooklime

This plant could more correctly be called the water speedwell, as it is closely related to the familiar blue-flowering wild plant. Yet the common name it most often goes by is brooklime, thought to be derived from the fact that it is frequently found growing wild in brooks on chalky ground.

It is a low, scrambling, aquatic plant that can hide a multitude of sins, such as unsightly exposed liners around the edges of ponds. The dark green, elliptic leaves are borne in profusion along branching, lighter green stems.

The dainty, royal-blue flowers appear on short, branching stalks in late spring or early summer and will fade and die off within a few weeks. The stems can reach lengths of 2m (6ft) or more, blanketing large areas.

Like watercress, brooklime can be a poor man’s water clearance plant. The aerial root systems do a wonderful job of cleaning, consuming excess plant food which would otherwise encourage algae.

The genus Veronica has over 200 species, and this is not the only aquatic form; however, it is certainly the one most readily seen for sale.

Veronica beccabunga, Plantaginaceae, Brooklime...

Veronica beccabunga, Plantaginaceae, Brooklime, inflorescence. Deutsch: Veronica beccabunga, Plantaginaceae, Bachbunge, Infloreszenz. (Photo credit: Wikipedia)

Veronica beccabunga can become untidy if it is not kept trimmed. Pinching out the tips of the long stems will encourage more side growth. Fully hardy, the leaves remain until late autumn. Most growth should then be removed.

Propagate by planting up trimmings, using ordinary garden soil, and keeping them moist for a week or two. They can then be placed into the pond.

Zantedeschia aethiopica, Arum lily or Calla lily

The arum lily, originally from South Africa, is perhaps as well known as a pot plant as it is for growing in the fringes of a pond. It is sometimes referred to as the calla lily, but should not be confused with its relation Calla palustris.

Zantedeschia aethiopica is quite hardy, as long as its crowns are protected in winter by a mulch of straw or bracken — or by at least 15cm (6in) of water! It is a highly variable plant, impossible to say with absolute conviction that it is hardy or half-hardy, deciduous or semi-evergreen or whether it is best as a marginal or a bog garden plant. When in full bloom, a large clump can be breathtaking.

In spring and summer, minute flowers congregate on fragrant yellow spikes, which come out from the middle of a large white spathe. The large, leathery deep green leaves, shaped like elongated hearts, are very dramatic.

The variety ‘Crowborough’ is taller and hardier than the species. ‘Green Goddess’ is particularly attractive, as spathes unfurl deep green and age to a pale, slightly ivory, emerald. ‘Apple Court Babe’ is a delightful miniature version, perfect for growing around a small pool or contained water feature. The chalk white spathes are carried well above the bright green leaves.

Grow zantedeschias in full sun or partial shade, in the damp soil of a bog garden or at the edge of a pond, in water 5-30cm (2-12in) deep. Plant and divide in spring. Flowers produce many seeds, which can be sown the following autumn or spring.

Ajuga reptans or Bugle

This is a hardy, spreading plant, originally from northern Europe. It is now available in several colour forms, ranging from the dark greenish-reddish wild type, to a lighter, tricoloured cultivar.

Ajuga is a shade-loving plant that is excellent for growing under trees and shrubs —as long as the soil stays quite moist. The irony is that the leaves are not seen at their best when the plant is growing in a shady place. Yet if you transfer the plant to a sunnier spot, it sulks and never performs its best. However, it is no greater a mystery than the one surrounding its common name. No one really knows why it is called bugle.

During the winter, the leaf rosettes close up and the larger outer leaves drop away, leaving the creeping stems (stolons) with plantlets at their tips, cleary visible. Bugle is particularly suitable for growing between the paving of an informal pond surround.

The flowers are daintily attractive — short spikes of small, lipped, purple blossoms appear in spring.

Ajuga reptans ‘Atropurpurea’ has purple flowers, with deep purple-bronze leaves; ‘Variegata’ has deep green leaves with cream margins; ‘Burgundy Glow’ has claret coloured leaves; and ‘Alba’, green leaves with whitish flowers. ‘Multicolor’ (also known as ‘Rainbow’ and ‘Tricolor’) has blue flowers and dark bronze leaves splattered with blotches of cream, pink and red.

Looking after bugle is easy. Plant it in autumn or spring. Give it a little general fertilizer in spring and water it well during dry periods.

The best way to propagate it is by division in spring. Individual plantlets can be planted directly into the soil.

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22. April 2012 by admin
Categories: Water Gardening/Water Features | Tags: , , , , , | Comments Off on Oxygenating Plants


In every pond or pool it is necessary to use ten oxygenating plants for every 20 sq. ft of surface area. They are essential to absorb carbon dioxide whilst they give off oxygen which-is required for the survival of fish for which they are also a source of food. They also provide shelter from strong sunlight and the cold. They will use up mineral salts from the water and help to keep the water clear and in a suitable condition for fish and other water plants survive. They are planted at the bottom of the pool between April and October, usually in containers which hold six plants.


Callitriche palustris. The Water Starwort, common in mud and ponds, the leaves borne in floating whorls in which are borne the minute green flowers during summer.

Hottonia palustris. The Water Violet, so called because of its violet-coloured flowers which are borne above the water during early summer. A member of the primula family, it has leaves which are deeply segmented.

Myriophyllum spicatum. The Spiked Water-Milfoil, its pinnate leaves borne in whorls of five, its crimson flowers borne in an erect spike. Myriophyllum verticillatum. The Whorled Water-Milfoil, a trailing submerged plant with its pinnate leaves borne in whorls all the way up the stem. During July and August it bears greenish flowers in spikes. Potamogeton crispus. The Curly Pondweed winch has toothed lettuce-like leaves, four-angled stems and bears its tiny petalless flowers in stalked spikes.

Potamogeton pectinatus. The Fennel Pondweed with thin leathery leaves and tiny flowers borne in dense spikes.

Ranunculus aquatilis. The Lodewort, which is found floating on fresh water pools, the leaves divided into three lobes. The white cup-shaped flowers, borne on the surface of the water during summer, resemble water lilies.

01. December 2011 by admin
Categories: Featured Articles, Plants, Shrubs | Tags: , , , , , , , , , , , , , , , , , , | Comments Off on OXYGENATING PLANTS


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