Portrait of a Medicinal Plant** (Original title: Portraet einer Heilpflanze. Tropaeolum majus L. - die Kapuzinerkresse. Merkurstab 1995; 48:357-62. English by A. R. Meuss, FIL, MTA.)

Tropaeolum majus L. - Nasturtium

Ruth Mandera, Ulrich Meyer

Morphology

Generally known only as an ornamental plant, nasturtium was brought from its native South America to Europe in the 17th Century. The Tropaeolum genus derives from Chile and Peru where 80-90 species are found, their distribution extending from the tropical rain forests to the snow line. The slopes of the Peruvian Andes are said to be the natural habitat of nasturtium.

Alexander von Humboldt (1769-1859) pointed out that the flora growing at different levels in the Andes actually reflect the plant cover of the whole earth. Lower down, where the climate is warm and damp, the vegetation is tropical, and in the cold atmosphere at high altitudes we find plants that also grow in the polar region. Coming from the warmth (metabolic) pole of the earth, close to the equator, the plant thus shows a tendency towards the cool (neurosensory) pole.

The plant has made itself at home in Central Europe, showing surprisingly lush growth and continuing to grow and flower throughout summer. It likes a rich soil and is often found on compost heaps, for example. Oddly enough, the stems do not come upright but stay close to the ground (Fig. 1).

Fig. 1. Nasturtium shoots stay close to the ground.

Nasturtium has no lignifying, permanent support tissues and has to depend on the support of hedges and fences if it is to reach any height. As a rule, the fleshy shoots lie on the ground, producing adventitious roots if covered with soil.

New leaves are continually developing at the shoot apex, with the first signs of flower buds immediately apparent in the axils. The young leaves are initially indented (Fig. 2).

Fig. 2. Development of individual nasturtium leaf.(1)

Even at this stage it is evident that the leaf is not attached to the stalk at the margin, which is the usual way, but the lamina is more or less centrally balanced on it (peltate leaf). As growth continues, the fleshy stalks elongate, turning away from the earth towards the light, and supporting the leaves, which now assume a horizontal position, from below. These are now approximately circular (Fig. 3 and 4). Form and orientation are remarkably like the floating leaves of water plants. Many other Tropaeolum species have crenate or divided leaves, which tend to be smaller, and it appears that large, juicy, rounded leaves are a special characteristic of Tropaeolum majus.

Fig.3: Shoot apex with young leaves.

Fig. 4: Typical peltate leaf.

An adequate water supply is vital in the hot summer months; even temporary dryness will cause the soft leaves to hang flaccidly. The firm shape can only be maintained if there is sufficient water. Hydathodes, cells active in the excretion of water, are actually found in the leaf margins. After a cool night in early summer, a droplet of water glitters at the end of every vein. This marked relationship to water also explains why the vitality of these plants is destroyed by even the slightest degree of frost in the fall. In no time at all they turn yellowish and translucent, collapsing completely as the freezing water expands and destroys their tissues.

In many European plants, vegetative growth terminates in an apical inflorescence. The early stages of flower bud development frequently go hand in hand with profound morphological and physiological changes in the green parts of the plant.

Fig. 5: Hairy bittercress (Cardamine hirsuta) a) Evolution of ground leaf. b) Foliage leaf metamorphosis.(2)

Figure 5b shows the sequence from first rosette leaf to the leaf subtending the flower of hairy bittercress (Cardamine hirsuta), Figure 5a the development of the second leaf in its rosette (see arrow).

If we compare this with the development of an individual nasturtium leaf (Fig. 2), the similarity is at first sight remarkable. Bittercress quickly overcomes this "juvenile stage," however, and goes into full expansion, division and contraction of leaf forms before it begins to flower. Nasturtium, on the other hand, "blows" the juvenile form up to considerable size and repeats the same form all its life. Flowering does not induce metamorphosis of foliage leaves.

The phenomena show that nasturtium has a strong connection to the earth's surface and to water in its vegetative leaf sphere.

The large sulfur-yellow or orange-red flowers immediately reveal another aspect of the plant. They grow singly from the leaf axils and stand erect on long, fleshy stalks. The flowers show none of the innocence of a buttercup that is open to the heavens. They are bilaterally symmetrical and face sideways, open to the animal that approaches them.

The colors of the five petals are brilliant, with the two upper ones occasionally showing dark striations running to the center (Fig. 6).

Fig. 6: The two upper petals of a nasturtium flower differ slightly from the other three.

The five sepals, which in other plants generally are as green as the foliage leaves, have a yellow tinge in nasturtium. The most striking feature is a long spur, which is also yellowy (Fig. 7). This has not developed from a sepal, which is the usual way, but is an outgrowth of the flower stalk.

Fig. 7: Bud with spur.

Axis organs such as roots, stems and stalks are characteristically receptive to earthly forces; they provide water and minerals for photosynthesis. Here, the green stalk assumes color, creating an internal space with nectar glands, and the characteristic spur of the nasturtium flower.

The distinction between leaf and flowering sphere is maintained, with vegetative organs such as leaves and stem only subject to the flowering impulse when very close to the flower (colored sepals, spur).

In their native habitat the flowers are pollinated by humming birds, their beaks entering deep down into the spur to reach the sweet and also somewhat hot (!) nectar. The impression is that the flower seeks to relate closely to the bird in form and color.

Fig. 8: Ripening fruit, showing stalk bending downward.

The fruit finally separates into three single-seeded parts, and the pulp, originally spongy with a high water content, dries up to become cork-like and shriveled.

Tropaeolum seeds contain an unusual fatty oil with an extraordinarily high content of unsaturated fatty acids. Oils and fats from plants in tropical regions characteristically contain saturated fatty acids (e.g. coconut and palm kernel oil). Unsaturated fatty acids are mainly produced in the cooler regions of the globe, examples being linseed and rape oil.(1)

The fatty acid spectrum of nasturtium oil reflects the "northern" character of a mountain habitat and the cool, damp atmosphere in which the seeds ripen.

Specific constituents

Morphologically, nasturtium deviates from the norm for flowering plants in many respects. It also has a special constituent that is not to be found in just any plant. (For mustard oil production in the cress family (Cruciferae), see Rolf Dorka's "Zur Beziehung von Landschaft und Heilpflanze - Teucrium und Nasturtium als Tuberkulose-Heilmittel" (relationship between landscape and medicinal plant - Teucrium and Nasturtium as tuberculosis medicines), Tycho de Brahe-Jahrbuchfuer Goetheanismus, Niefem-Oeschelbronn, 1994.) Nasturtium produces benzyl isothiocyanate, a volatile mustard oil with an acrid, penetrant odor. This is hot to taste, and in highly concentrated, pure form irritates the mucosa. Benzyl isothiocyanate may be regarded as a thoroughly fiery, sulfurous compound.

The mustard oil is present throughout the plant but is not immediately perceptible. It only develops its characteristic odor and taste when the tissue is destroyed, e.g. by chewing a leaf or a flower. The plant "hides" the sulfurous qualities of the oil by binding it to sulfate (a salt-like or saline form of sulfur) and sugar. The intact plant thus contains a "benzyl isothiocyanate sulfate glycoside." This, in fact, makes the lipophilic benzyl isothiocyanate water- soluble, so that it can be deposited in the vacuole. Metabolic end products are characteristically "excreted" to the inside in vacuoles. Volatile oil plants often let their material flow freely out into the atmosphere; nasturtium keeps its mustard oil hidden deep inside the cell. When the plant tissue is damaged, the enzyme myrosinase comes in contact with and is able to act on the glycosides and "detonate the mustard oil bomb," as Zurich plant physiologist, Matile, once put it. Nasturtium is able to control a highly sulfurous compound such as benzyl isothiocyanate in saline form and store high concentrations of it in all its organs.

The morphology shows tension between lush vegetative growth and powerful flowering processes for the whole period of development. In the plant's constituents the opposite qualities of Sal and Sulfur encounter each other.

Medicinal actions

Since the early 1950's, nasturtium has proved widely effective in the treatment of respiratory and urinary infections. Benzyl isothiocyanate inhibits or kills Gram positive and negative bacteria and fungi. To date, resistance has hardly ever developed! It is interesting to note that the nasturtium action is exclusively on the lungs, kidneys and bladder, organs that deal intensively with the interplay of air and water.

Urinary tract infections frequently follow a chill, and this can be countered with this "northern" yet thoroughly sulfurous plant.

Compared to phytotherapy, where it is given only by the oral route, nasturtium plays a key role in the Wala acne preparations for topical use. Acne vulgaris presents a paradox in skin metabolism. On one hand hyperkeratosis produces blackheads. The masses of hardened keratin do not dissolve easily. On the other hand sebaceous gland hyperactivity leads to seborrhea. The excess sebum provides a nutrient base for bacteria which break it down into fatty acids that cause skin irritation. Fatty acids are normally broken down with the help of endogenous lipases in the human food metabolism.

With acne, we have a pathological degradation of fats by foreign organ- isms on the skin, i.e. in the neurosensory system. Inflammatory efflorescences go hand in hand with this.

Nasturtium may be said to be able to overcome the two fundamental pathological processes in acne. It avoids all hardening processes and also has a superb ability to control its mustard oil metabolism, keeping it in its proper place (the vacuole).

Nasturtium in paintings

Nasturtium is a popular ornamental garden plant, but we know only of three paintings that include it - Henri Matisse's La Ronde and Hannah Hoech's Glaeser (Figs 9, 10). Henri Matisse (1869-1954) has painted at least two versions of La Ronde, both in 1912. We shall limit ourselves to the one which in our opinion is more characteristic. Hannah Hoech (1889-1978) was above all esteemed as a Dadaist. Glaeser was painted in 1927.

Fig. 9: La Ronde, by Henri Matisse.

Fig. 10; Glaeser, by Hannah Hoech.

It is perhaps not by chance that nasturtium appears so rarely in works of art. It is not a cut flower to be portrayed at leisure - its "water form" will survive only for a short time, even if put in water.

Both paintings show the round, peltate leaf. Matisse has the shoots forming an approximate circle. The large, big-bellied vase is in deliberate contrast placed on a small, square turntable. Behind the table dancers join in a circle for their round dance.

Hannah Hoech also used the contrast between square and circle, with the table top not only square but put at an angle. On the table are a number of roundish vessels, marvelously showing the play of light and dark, with circular reflections. A nasturtium leaf lies among the circles and vessels. Both artists thus caught the characteristic gesture of the peltate leaf intuitively and with seeming ease.

Ruth Mandera, Ph.D.

Ulrich Meyer, R.Ph.

References

1 Suchantke A. Die Zeitgestalt der Pflanze (1973). Goetheanistische Naturwissenschaft Band 2, Botanik. Stuttgart 1982.

2 Bockemuehl J. Bildebewegungen im Laubblattbereich hoeherer Pflanzen (1966). Goetheanistische Naturwissenschaft Band 2, Botanik. Stuttgart 1982.

3 Errenst M. Die Waermeoffenheit von Fetten und Wachsen. Jahresbericht des Carl Gustav Carus-Institut, Niefem-Oeschelbronn 1992.

Photographs byJohannes Roth-Bernstein.