Marginal Plants For The Pool

If you are fortunate enough to live in the country or enjoy tramping across the countryside around lakes and natural ponds and rivers, you can hardly have failed to notice how plants grow in their natural habitats. Frequently a number of species will grow in profusion together, inter-mixed in a haphazard fashion. But you will also see, especially if you follow a river for any distance, that at one spot a particular plant flourishes only to disappear completely round the next bend where another kind has taken hold. This in its turn vanishes and on the far bank a third plant has colonized, and so on. And so it should be in a pond. In a confined space, plants which are mixed together only create a confused vision. Similarly, one specimen of ten plants, planted one after the other, will present a scheme lacking in character. What one should aim for is a mass of one plant followed by a showy mass of another. Almost all marginal plants are easily propagated by division, so even if you obtain only one specimen initially, within a season or two you can easily achieve the right effect. Firm, definite groupings of a few plants is very much more desirable than a hotch-potch of many.

Marginal plants, for want of a definition, are those which grow in shallow water or in soil that is saturated in water. They have a flowering period which ranges from early spring until autumn. One plant precedes all. That is the lovely Caltha palustris, often called Marsh Marigold or Kingcup. I do not think there is any other waterside plant that has given me more pleasure. There comes one of those early spring days when the breeze carries the heady smell of new growth. A new warmth pervades the air and there on the edge of the pool the Marsh Marigold has opened her brilliant yellow flowers. The quality of that yellow seems to me unequalled. I can picture now, in my mind’s eye, spring evenings when the sun has just passed over the pond and the flower of the Marsh Marigold seems almost luminous against the dank brown that still remains of last year’s growth. The Marsh Marigold produces a mass of flowers that will remain in flower for several weeks. (I also grow the lilac-flowering Rhododendron Trae-cox’and masses of the early Erica ‘Springwood White’, so that new life around the pool begins not long after the New Year.) The Marsh Marigold abounds throughout Europe and parts of North America. It reaches a height of about 30 cm., grows best in moist soil or very shallow water and is easily propagated by seed or division. A double variety, Caltha palustris flore pleno, is slightly smaller and less vigorous, but it can produce such a wealth of flowers as to almost conceal the plant beneath them. An altogether larger version is available in Caltha polypeiala which grows up to 60 or 90 cm. And from the Himalayas comes a small white version, Caltha palustris alba, which may grow no more than 15 or 20 cm. High. These are all excellent plants for concealing an unsightly piece of concrete margin. In shallow water, their generally bushy habit will obscure the margin behind, while planted around the pool, some of the leaves will tend, conveniently, to flop informally over the edge of the bank.

Equally suitable for hiding a few metres of ugly margin is the Bog Bean, or Menyanlhes trifoliata, so called because its light green leaves are divided into three well-defined parts. Growing about 30 cm. High, the Bog Bean has a horizontal rootstock and enjoys stretching across the surface of the water rather like a floating plant. And even if you have no margin that needs concealing, the Bog Bean is well worth growing for its unique flowers. They come just about the time the Marsh Marigold is on the wane or is over. Conspicuous rich pink buds peel back to reveal five snowy white petals which are crested on their surface with long, curly white hairs and these give the flower a fluffy or even a frosty appearance. This is certainly a flower worth examining closely. Look at how snugly the stamens fit around the base of the petals, each with their bright yellow pollen load, and how the light green style protrudes just above the level of the curling hairs. There is no daintier flower among the marginals; a watchmaker might baulk at constructing anything so delicate. Common to many boglands throughout Europe, Asia and North America, Menyanthes trifoliata is a plant of vigorous growth but one that can be cut back easily.

Brass Buttons, or Cotula coronopifolia, is an-other plant that enjoys scrambling about the margin in shallow water. The flower consists of a small disc of matt yellow, in itself not very exciting, but where there are tens of these flowers appearing together, as they do during the summer, the effect is lovely. The flowers bend over slightly on top of their thin, elegant stems, looking like so many miniature periscopes. The plant is unlikely to exceed 25 cm. In height. In winter it may die back altogether, as an annual, in which case you are dependent upon the seeds. So do not renew the soil in the basket or around the margin until the new plants have come up the following spring. In the Southern Hemisphere, in South Africa and Australia, where Cotula coronopijolia is a native, it can tend to be rather invasive. In more temperate zones it can be introduced safely.

The same cannot be said about the Great Water Plantain, Alisma plantago-aquatica, a plant common throughout parts of the Northern Hemisphere. Grown in moist soil or shallow water, it is far from fussy; it throws up elliptic, erect leaves on long stalks, reaching a height of anything from 30 to 90 cm. In mid to late summer appear the tiny nondescript pink or white flowers. What makes the plant so attractive is the pyramidal panicle upon which the flowers appear. Less attractive is the Water Plantain’s habit of setting seed anywhere and everywhere. If you introduced this plant then be sure to cut out the panicles as soon as the flowers are over. A more suitable form, because less rampant, is Alisma lanceola-tum which has long slender leaves and height of about 30-40 cm. But it is also rarer and you may not find it easy to obtain.

No such problem should arise with the popular little Bog Arum, Calla palustris, and since it grows no more than 25 cm. In height and is compact in habit it is an obvious choice for the small pool. It thrives with 5 cm. Of water over its crown and produces a small white trumpet flower in summer. Comes the autumn and the flowers have been replaced by fruits of brilliant scarlet. A more familiar arum is Zantedeschia aethiopica (also known as Calla aethio-pica and Richardia africana) or Arum Lily which grows to a height of 60 to 90 cm. And bears magnificent trumpet flowers of pure white with a yellow ‘poker’ or spadix within. This plant is not really hardy however, and should be wintered in a cold house which is frost-free. Alternatively, if you experience only mild frosts, the Arum Lily should survive in the pool the whole year round if it has 20 or 30 cm. Of water above its crown. Another plant with white trumpet-shaped flowers is to be had in Lysichitum camischalcense. Whether it be planted in moist soil or shallow water this plant does require deep soil: 50 cm. Is not too much. Once established it is a difficult plant to lift intact. Raising the plant from seed is rather easier though several years must elapse before the young plants can be expected to flower. The leaves, which vary from 30 to 100 cm. In length, arise almost stemless from the base of the plant. Even when the plant does not attain its maximum height, I find its broad leaves rather too bulky in appearance for a small, compact pool. It looks best when one has plenty of space and other shrubby plants with which it can harmonize. This applies even more to the somewhat taller and broader Lysichilum americanum or False American Skunk Cabbage. However, where space permits, this plant produces a welcome contrast to camlschatcense and indeed Calla palusiris in bearing yellow trumpets.

White and yellow are common colours among marginal flowers, whereas blue is comparatively rare. The prostate and rambling Veronica beccabunga or Brooklime produces small blue flowers on racemes in the leaf axils. Grow the plant if you would like to try the leaves as a spring salad, but it has to be said that so far as the flowers are concerned they are rather dull and inconspicuous. A much more brilliant blue is to be had in the Water-Forget-Me-Not or Myosotis scorpioides (palustris) and especially in the improved ‘Mermaid’ strain. The plant varies very much in height, but 20 cm. Would be about average; it flowers profusely over a long period and sets seed easily, so that you should have a fine mass of this showy little marginal in a matter of a few seasons. And it thrives in shade. Quite a few plants have been called Forget-Me-Nots from time to time, but the water plant has the greatest claim to the name on account of being named such by German botanists way back in the Middle Ages. But there are more romantic accounts of how the Myosotis received its name. One such legend, from the sixteenth century, tells the story of a knight who was taking a stroll with his lady-love along the banks of the River Danube on the eve of their wedding. The lady, to her distress, spotted a spray of these flowers being carried away by the river. Instantly the knight plunged into the river to retrieve them. He reached the flowers only to find that the current was too strong for him to return to the shore. As he was swept by his lady-love he threw the fatal flowers on to the bank beside her, with the exclamation: ‘Vergiss mich nicht!’ — ‘Forget-me-not!’ It is said too that youths in medieval times garlanded their loved ones with chains of Forget-Me-Nots. The plant is small enough for the smallest pond and conspicuous enough for the largest. For the same reason Water Mint or Mentha aqualica should have a place in any water scheme. It will grow in damp soil or under several centimetres of water. The leaves are rather hairy and are found in two colours, a dark maroon colour and a bright green. In the wild, it is commonly found in wetlands adjacent to rivers and lakes, and you will often find plants with both these colours living within a few metres of each other, and sometimes both colours on the one plant. A keen observer will easily discover why. In shade, where the plant does well, the leaves remain green, but when exposed to sunlight for any length of time they soon turn to a purplish maroon hue. Under very favourable conditions Water Mint can reach a height in excess of a metre. But in a confined space the likely height is about 30 cm. Keep a sufficient number of the plants from which to pluck off leaves to flavour your potatoes. And enjoy the bright whorls of lilac-blue flowers that appear at the end of the summer.

Blue flowers are also produced by the Pickerel Weed or Ponlederia cordala, some say the best blue flowers of all water plants. But the flowers apart, this is a handsome plant by any standards, sending up light green cordate or heart-shaped leaves on long stalks, and rising 45-75 cm. Above water level. It does best in water no more than 12 cm. Above its crown, and towards the end of summer the flowers appear on spikes. Not all the flowers on any one spike will necessarily open at the one time, which can give the spike a slightly moth-eaten appearance, it seems to me. But when the Pickerel Weed is grown in sufficient numbers, the individual spikes give way to a mass effect of medium blue. Pontederia lanceolala has, as the name suggests, rather more lance-shaped leaves and it grows very much larger, often to 1.5 metres in height, but this species is not fully hardy.

Even more dramatic than the lance-shaped leaves of the Pontederia are the arrowhead-shaped leaves of Sagiitaria sagillifolia. The plant, also known as Common Arrowhead, is best stood in 10-15 cm. Of water but it will often thrive in greater depths. The roots need confining as they are stoloniferous and spread rapidly. Occasionally some of the leaves may float on the water, but generally they rise, more or less perpendicularly, 40 cm. Above the water surface. The white flowers are produced in midsummer. A larger variety comes in Sagiltaria japonica, but the one to obtain, if at all possible, is the double form, Sagittarin japonica flore pleno, which grows to much the same size as the Common Arrowhead but much more slowly, and there is no need to contain the roots. And the flowers are so double as to seem almost like small snowballs. For effective foliage and flowers this plant should rank high on any choice list of water plants.

Effective foliage is a good reason for growing Ranunculus lingua (especially the larger grandiflora form), which often reaches a metre in height. Green sword-shaped leaves come off a broad stem knuckled like bamboo and flushed with a hue of dark pink. Ranunculus comes from the Latin name for frog, Rana, an allusion to the fact that many of the species inhabit wet places. As the common name of the plant, Tongue Buttercup, implies, it produces flowers very like the common buttercup of the meadow that we all picked as children, only in the grandiflora form, they are somewhat larger — often exceeding 5 cm. Across. The plant can be expected to flower throughout the summer and even into the autumn. On account of its rather thin flower stems, however, the plant can look rather gangly and windswept after stormy weather. If you have a sheltered corner, place it there in shallow water, and contain the stoloniferous roots which can send up shoots at a considerable distance from the parent plant.

Less susceptible to wind is Butomus umbellatus or Flowering Rush. It grows to much the same height as the Tongue Buttercup, around a metre, and thrives in water up to 10 cm. Deep. The long, thin leaves are shaped rather like stilettoes and are occasionally twisted. In midsummer come the flowers, sometimes light pink, sometimes almost maroon. Rising from their stalks, the whole flower head resembles the structure of an inverted umbrella, hence the name umbellatus. A single umbel may produce as many as thirty flowers. The plant is found in Europe and Asia, and its colourfulness and shape make it an obvious choice for the garden pond.

Some gardeners feel the Bur Reed or Spar-ganium erection is not a plant worth including in the garden. True, its strap-like leaves which rise from the base in two distinct ranks are not of great interest and the flowers are not colourful. Nevertheless, the flowers, the large female burs and the smaller male ones, do create an unusual design unlike any other plant. So if you have a keen eye for structure this is a plant you might care to grow. It is quite happy to stand in water of any depth up to 45 cm., a useful feature since few other plants will tolerate that depth. However, if you have but one bay of that depth, then the Bur Reed should hardly be your first choice. That distinction should surely go to the Golden Club, Orontium aquaticum, a versatile and highly spectacular plant. The leaves are of a dark velvety green on their upper side and of a silvery sheen underneath. When planted in deep water the leaves tend to float, whereas in moist soil at the pond’s edge — where the plant will do equally well — the leaves grow more or less upright to a height of about 45 cm. Then, of course, the contrasting shades of the leaves can be appreciated to the full, especially when a light breeze creates a shimmering effect. In spring and early summer, the Golden Club produces a large number of strikingly white stems or spadices, at the ends of which appear the bright yellow flowers. The effect is of a brilliant white matchstick with a yellow head. Matchsticks however, do not come 30 cm. Long and as thick as your finger. So it is both the size and colour of the flowers as well as the leaves which make the Golden Club so fine a waterside plant. It does have the disadvantage of requiring deep soil, 45 cm. At least, and once established the plant can only be lifted with difficulty. Propagate by seed, starting them in shallow water.

Everyone who owns a pond will want to grow Typha, and with good reason. The long rush-like leaves and the tall brown pokers of the Reed Mace or Bulrush as Typha is commonly called, are for most people inseparable from water. The question is which Typha to grow. The commonly found Typha latifolia is a magnificent plant, but one which can produce a veritable forest of vegetation two or more metres in height. Clearly this is only a plant for lakes and very large water schemes. The more slender Typha angustifolia can reach a similar height, but will remain somewhat shorter if kept within bounds and it should still flower reasonably well. In the wild, the two plants can be distinguished by the fact that the leaves of Typha latifolia are mostly 1 cm. Or more in width, while those of Typha angustifolia do not usually exceed 0.5 cm. Shorter species of Reed Mace, namely Typha Shuttleworthii and Laxmanii are perhaps more suited to the garden pool, but these plants are not so easy to come by. So, for most gardeners, the best choice is Typha minima, a dwarf species unlikely to exceed 50 cm. In height. This little plant does have a drawback, however. Its flowers are not so elongated and so are less poker-like than are those of the other species. Sometimes, in fact, the flowers of T. minima are almost globular. The mace is the symbol of kingship; and the name Reed Mace derives from the fact that Rubens and early Italian painters depicted, in their Ecce Homo paintings, the crucified Christ holding the Typha reed in one hand. The reed has also a place in Greek mythology. In one legend, the God Apollo, so incensed at King Midas preferring the singing of another to his own, clapped a pair of ass’s ears upon the unfortunate king. The king’s barber discovered them and felt quite unable to contain so awful a secret. So he hid the secret at the foot of a clump of bulrushes. The reeds could not contain the secret either, and while rustling gently in the breeze, kept murmuring: ‘King Midas has ass’s ears’. Provided your children are at an age when they can treat fire sensibly, the pokers of the Bulrush can make dramatic torches at a barbecue. Cut the pokers down at the base and allow them to dry indoors. Then soak their heads in paraffin or methylated spirits. Placed in holders around the pond they make a spectacular, if shortlived, form of illumination.

The name bulrush, a corruption of Pool Rush, really refers to Scirpus lacustris, a broad and tall plant, too invasive for consideration in a garden. And much as one might admire the dark green, triangular foliage of Scirpus maritimus of universal distribution, it is much too vigorous for any setting other than the largest. To be sure, it is a fine plant for a well-designed palio pond, attracting wild fowl to your pond. It provides them with excellent cover. But let it be emphasized, water-lilies and choice aquatics are not compatible with ducks, which will eat all before them. For the ornamental pond, the obvious choice from the Scirpus genus is Scirpus Tahernaemontani zebrinus. The plant is known variously as the Porcupine Quill Rush on account of its smooth, slender and sharply pointed leaves, and as the Zebra Rush on account of its very distinctive cream and white bands which ring each leaf from top to bottom. This feature is unique in the plant kingdom. Plant in clumps in shallow water and this rush will grow to about 1.4 metres and will be a most conspicuous element in any pond, especially when the surface of the water is quite still and the bands are doubled by reflection. Should any plain green leaves appear, these should be cut out in case the plant intends to revert to its unvariegated state. Propagation is easily achieved by division. For a striped, rather than a banded effect, include a clump of Manna Grass or Glyceria ses narrow, grass-like foliage striped with no less than three colours: green, yellow and white; in fact four colours, because in spring and autumn a rosy tint creeps into the foliage. In a small basket this lovely plant may grow no more than 30 cm. High. When given all the space it requires, Manna Grass will reach a height of about 90 cm. It spreads rapidly in shallow water and moist soil, so it is as well to restrict its roots.

There are one or two species from the Juncus genus which are worth including in the pond. The majority are, as a rule, far too vigorous and tenacious to introduce with safety. The first exception is juncus effusus spiralis which, unlike its relations, is a comparatively modest grower. It is a curiosity plant and the delight of any child. Its leaves grow in wiry spirals, often with the uniformity of a corkscrew. Old timers nicknamed it ‘Harry Lauder’s walking-stick’, for it does rather resemble the crooked walking-stick of that famous Scottish comedian. The second exception is juncus ensifolius which grows 30-50 cm. High. The foliage is rather undistinguished, but towards the end of the summer the plant produces little brown florets which at a distance appear as jet black. They might be the brooms of some miniature chimney sweep. Shallow water or moist soil suits both plants.

If you have a flower arranger in the house, a planting of Sweet Galingale, Cyperus longus, will be appreciated, for it is a favourite source of greenery for the florist’s art. Its darkgreen, slender stems which rise perfectly straight for most of their length and then gracefully curve over, make excellent background material. And you need never fear cutting off too many of the stems. Sweet Galingale is a trenchant plant and will throw up large numbers of these decorative stems year in year out. The bulbous root, incidentally, is edible. Another highly decorative plant in this genus is Cyperus altemifolius or Umbrella Grass. As a native of Madagascar it is not fully hardy, so it should be grown in a basket and wintered indoors. Apart from that, the plant is not fussy, being equally content either in shallow water or on the bank. It grows to about 90 cm.

If you have a summer-house with a wooden or stone floor, then by growing the Sweet Flag, Acorus calamus, you can revive an ancient custom. Crush the leaves and they will impart a pleasant perfume not unlike a tangerine orange. This feature of the plant made it highly sought after for strewing over the floor in medieval and Renaissance times. As the leaves were crushed by being walked upon, so the great halls and rooms of olden times were filled with the Flag’s sweet aroma. At least so we may believe was the case on occasion, but not always. When the great scholar Erasmus visited Oxford around the end of the fifteenth century, he was not enamoured to find that the rushes on the floors harboured ‘expectorations, vomitings, the leakage of dogs and men, ale-droppings, scraps of fish’. But so fond was Cardinal Wolsey of the Sweet Flag that he had the strewings at his palace, Hampton Court, renewed daily. Such extravagance brought the cardinal much criticism. Moist soil or shallow water suit the Sweet Flag equally well and in either situation it grows to about 70 cm. A Japanese variety, Acorus gramineus, grows to about half the height of calamus. Variegated forms of both are available, the young leaves being vividly striped in green and creamy yellow, fading somewhat to a paler colour in late summer. When Sweet Flag was in short supply or unobtainable, the odourless Yellow Flag was used instead. Although only second best as a floor strewing, the Yellow Flag has had a rather more elevated history than the Sweet Flag, since Louis VII of France took its lovely flower for use as an armorial device. For this reason it is known as ‘Fleur de Louis’ as well as ‘Fleur de Luce’ and ‘Fleur de Lis’. Around Orleans in France arose a curious legend whereby it was believed that the seventh son in a family with no daughters intervening, known as a marcon, had somewhere on his body the imprint of the Fleur de Louis and possessed magical powers. Whoever was suffering from ‘king’s evil’ or scrofula had only to touch this imprint or even be breathed upon by the marcon and his malady would disappear.

The Latin name for Yellow Flag is Iris pseuda-corus, a name presumably chosen to signify its similarity to Acorus calamus. The two plants are often found together in the same boggy situations and along river banks, but they are not so similar in appearance. Acorus has dark green leaves, comparatively thin and straplike, often with undulations appearing along the edges for a short distance. The leaves of Iris pseudacorus are light green with a distinctive blueish tinge and they are shaped like many sword blades standing with their tips upwards. Although the flowers of this iris, like that of almost all irises, evoke a supreme sense of fineness and delicacy, the plant itself is very robust. Possessing a tough and vigorous rhizome. Iris pseudacorus is to be found in large numbers in many rivers and wetlands throughout Europe and beyond. If you include it in your pond an energetic programme of cutting back will be necessary from time to time. A more modest grower is found in Iris pseudacorus variegatus with its cream and green stripes running the length of the leaf. It has the same flower as the un-variegated form, while a lighter, lemon yellow flower is produced by Iris pseudacorous bas-tardi. Seeds from the ordinary plant very occasionally produce bastardi. The plant has the advantage of being unusual if not rare, but the flowers are much less conspicuous than those of the common form. From North America comes Iris versicolor, or Blue Flag, which is almost identical to Iris pseudacorous except the flowers are purplish-blue instead of yellow. All these irises will do well in wet soil or shallow water and they grow up to a metre in height.

The smaller blue Iris sibircia with its grasslike foliage is a particularly versatile plant. It will grow in an herbaceous border with a reasonably high moisture content as well as in a basket submerged in the pond provided its crown is no more than barely covered with water. There are several cultivars of this iris ranging from the deep purple of ‘Caesar’ to the pure white of ‘Snow Queen’. For deeper water, up to 10 cm. Above the crown, grow the true water-loving Iris laevigata, or Iris kaempferi. These two plants need to be distinguished, because whereas laevigata relishes water over its crown throughout the year, kaempferi does not. Kaempferi comes from the rice fields of Japan which are flooded during the summer months and are no more than moist during the winter ones. By growing kaempferi in a basket, it can be placed in the pool in spring once growth has begun and removed in autumn. Otherwise try to find a spot which is boggy but not totally saturated. There are a number of ways in which his kaempferi and laevigata can be differentiated. The leaves of kaempferi have a distinctive raised mid-rib which can be easily felt and which laevigata lacks (the name laevigata comes from the Latin for smooth). The standards of kaempferi never exceed two thirds the length of the falls and are often shorter than that.

The falls are very broad — the plant’s most conspicuous feature — and they often stretch out almost horizontally. The seeds of kaempferi are flat, circular or nearly circular discs, contained in a capsule no more than 2.5 cm. Long. In Iris laevigata the standards and falls are roughly of equal length. The seeds are semicircular and contained in capsules 5 cm. Long. Both these plants require a rich, loamy soil. Kaempferi does not like soil that contains chalk or lime while in winter it will appreciate an occasional dose of liquid manure. Propagation is easily achieved by seed or division. Seeds planted in autumn should germinate the following spring, but it may be several years before flowers are produced. It is a good idea to remove the seed capsules in autumn whether or not you intend using the seeds, as this will encourage flowering in the following year.

All these marginal plants can be grown in the pond. Many of them can, as pointed out, be grown in moist soil around it. But there are many more moisture-loving plants which will not tolerate saturated soil. To grow these plants one must think in terms of a bog garden.