Popular Science Monthly/Volume 53/October 1898/Plant Life of the Canary Islands
|PLANT LIFE OF THE CANARY ISLANDS.|
THE Canary Islands have appealed to the world under various aspects. The ancients idealized them, mediævals fought over them, and moderns are analyzing them. The fire-tried rocks, crevasselike gorges, and confused mountain masses make a fascinating field for geologists; curious Coleoptera attract the entomologists; hills, valleys, and shores abound in interesting plants; the climate and meteorological conditions have been the study of many doctors.
One's first view of Grand Canary is most disappointing. The "Fortunate Islands" of Lucian—abounding in luscious fruits, covered with luxuriant forests, where the sun always shines, and Nature, unaided, liberally supplies all needs—are a mental picture which is sadly shattered by the reality. The low coast is buried in shifting sand blown across from the African desert. Behind it are bleak hills colored a dreary gray by drought-loving euphorbias. We wonder where the materials for such glowing descriptions as Humboldt's, Leclerq's, Edwardes's, and Berthelot's are hidden.
Closer acquaintance banishes our doubts, and we soon learn to love this land of crags, and find from hilltop, in valley, and on seashore views unsurpassed by the oft-sung beauties of Switzerland or Norway.
The flora of the islands was studied thoroughly sixty years ago by Webb and Berthelot, who with indefatigable zeal scoured peak and plain. But they were unable to visit personally two of the islands (Gomera and Hierro), and spent only a short time on Lanzarote and Fuerteventura. The results of their studies of the phanerogams were published in three large volumes with fine plates—now out of print and very difficult to obtain. Since that time various botanists have spent longer or (usually) shorter intervals on the islands, but no other extensive work has been undertaken, and doubtless many plants, either undiscovered by these pioneers or introduced since their time, or reported by them from only isolated localities, remain to be studied; and the scattered results of the different investigators should be incorporated into a complete botany of the archipelago.
The flora of the archipelago includes, according to a recent publication, twelve hundred and twenty-six species of vascular plants; four hundred and fourteen of these are found nowhere else in the world, or only in Madeira, the Azores, or the Cape Verd Islands. These three island groups together with the Canaries constitute the so-called "Atlantic Islands"; all are of volcanic origin and have many features in common. They are, moreover, connected by a narrow submarine plateau which, perhaps, argues a former means of more intimate communication.
The general character of the Canary flora is that of the Mediterranean region. Some species show Indian or South African relationships; still fewer have American affinities. The Gulf Stream still brings drift, including seeds and the branches of trees, from the Bermudas by way of Madeira to our islands. Columbus, who made frequent visits to Gomera, found on its shores fragments of West Indian
plants, and was thereby strengthened in his belief in a western continent. An occasional east wind—such as sometimes brings armies of grasshoppers—may carry seeds from the Sahara region. Indeed, the woolly seeds of Gomphocarpus fruticosus are said to have been brought on the spiny legs of the grasshoppers. But the prevalent winds and ocean currents of to-day form a barrier between the Canaries and the continent, and among the sixteen hundred and twenty-seven species enumerated from Morocco by Ball, only two hundred and sixteen are found on these islands. That the former more effective means of communication must have been of very remote date is clearly evidenced by the great development of peculiar species of continental genera. Moreover, Saporta proves that types now found only in the Canaries (or perhaps also in Madeira, the Azores, or Cape Verds) existed in Europe in the Tertiary period. Such are the native laurel, viburnum, and pine. The persistence here of these ancient types speaks strongly for the constancy of the climate—to-day a strong attraction to invalids—for the average summer and winter temperature hardly differ ten degrees.
The great age of the archipelago is further indicated by the marked individuality of the flora of each island. The species have had time to develop in various directions under the influence of the different conditions to which they have been exposed, and the difficulty of obtaining foothold in the rocky, volcanic soil (pointed out by Christ) has doubtless often prevented the intermixture of the parent and derivative forms, so assisting in the formation of new species. For it must have been only rarely that the seeds or fruits brought from one island to another, or from the mainland, have found themselves in places favorable to development. So speciesmaking has progressed, and as a consequence we find Teneriffe with twenty-seven species known from no other region. Grand Canary with seventeen, Palma with eleven, Gomera with ten, Hierro with three. Fuerteventura and Lanzarote, on account of their greater proximity to the African coast, have a somewhat more continental aspect of vegetation than the more westerly members of the group. They have together thirty-two species which are either confined to them or found very seldom on any of the other islands. Other peculiar species are common to two or three islands only.
The soil is very rich. With irrigation three harvests a year are regularly gathered on Canary and Teneriffe. The water supply is largely kept up by the cloud belts, which even in the driest seasons form almost daily over the higher mountains, feeding the springs there which are the life of the land. But, as has already been said, the rocky, volcanic nature of the coast forbids the entrance of many plants, and this fact has had great influence on the character of the flora. The craggy hills and stony shores have a decidedly desert aspect, and adaptations to drought in the form of fleshy, hoary, and coriaceous leaves and stems abound. Euphorbias take the place and have the appearance of the cacti of American deserts. Fleshy Crassulaceæ of the Sempervivum group are more abundant here than in any other part of the world. There are twenty-two species of them which are found nowhere else. Such fleshy plants are not confined to the volcanic wastes and shores. They project from the most precipitous and rocky sides of the gorges. The urban flora, which makes Laguna and other old towns so picturesque, and which Berthelot describes as largely a duplication of that of the ruins
between the members of widely separated orders (e. g., Euphorbia balsamifera, Sonchus Kleinia, species of Sempervivum, Senecio, and Statice). Is this also a means for the reduction of transpiration?
The same question (this time as regards the flowers) applies to the species whose blossoms close soon after noon. The volcanic wastes, brilliant in the morning with the bright flowers of Helianthemum., Fagonia, Calendula, Sonchus, and Anagallis, are in the afternoon like a house where the lights are gone out, for all the blossoms have gone to sleep, and there is nothing in sight but brown soil and dull-green leaves.
The curious plants with twiglike leaves seem also to have been provided against too great loss by transpiration. Such are Plocama, a strange rubiaceous shrub which looks like a diminutive weeping willow; Genista rhodorhizoides, called by the insulars "retama," whose flowers appear even in the dry season, and, in the time of rain, whiten the hills; Spartium junceum, an even more perennial bloomer, with brilliant yellow blossoms brightening dusty waysides; Sonchus spinosus, of the volcanic regions, generally afflicted by the dodder which bears its name; Asparagus, Ephedra, etc.
As one travels from the shore to the interior, the flora slowly changes as the temperature falls. In Teneriffe there is a gradual and complete transition from subtropical to purely arctic vegetation. Valleys, fields, hills, and gorges have their own characteristic plants.
The hillside flora is an interesting one. Often the whole lower part will be covered with an ugly growth of Opuntia, the prickly pear. There are two wild species, both very abundant and greatly esteemed for the sake of the pulpy fruit, which in the drier islands, where rain sometimes does not fall for several years, serves as a substitute for water. One was formerly extensively cultivated as the host-plant of the cochineal insect, but the discovery of aniline dyes has nearly ruined this industry. Still many fields exist, and the bare-footed women are yet to be seen passing between the spiny rows, putting the insects on each plant by hand. In the wet season, after being sown with the parasite in this way, the branches are tied up in
white cloth to prevent the insects being washed off by rain, and a field so doctored is ridiculously suggestive of a regiment of bandaged feet.
These prickly things are disagreeable enough to the climber, but above them there is a most attractive region. Asphodels bloom in prodigal luxuriance. Gladioli have a brief period of gaudy predominance.-Fragrant white Amaryllidaceæ are there, and the dainty-flowered Romulea. Hidden among the rocks grows the little native Jack-in-the-pulpit. The common brake, Polypodium, and Davallia
are here as everywhere among the rocks, and more rarely the sweet-scented fern and a species of Notholæna peep from the chinks of the crags. Gray clumps of the giant Canary Euphorhia rise sometimes to a height of twenty feet, and among the great columnar branches twine coils of spiny Rubia. There are several woody species of dock often seen on the steeper hillsides, and occasionally a shrubby Convolvulus. The Echiums reach great development on the islands. There are several peculiar species. The immense spikes of white or blue flowers are a common and striking feature of the landscape. Shrubby Hypericums also abound, both on hillsides and in barrancos.
The so-called "barrancos" are a rich field for the collector. They are deep, narrow cracks between hills which have been sundered by volcanic disturbance. Erosion has had little or no part in their formation. Many of them are not watered at all, and if followed to their sources are found to end blindly among the hills. In some the winter rains collect and remain as stagnant pools or slow-flowing streams through a part or the whole of the year. Others are beds of perennial brooks fed by springs among the hills, and sometimes, in seasons of heavy rains, the waters rise above their narrow channels and rush in floods to the sea, causing great devastation among the fields and homes of the farmers. Teneriffe, Canary, Palma, and Gomera are supplied with such streams and springs. The whole island of Lanzarote has only two insignificant and inaccessible springs; Fuerteventura is slightly better off, while Hierro is entirely dependent upon rain water, which is carefully stored in cisterns.
Valleys, of which there are notable ones—such as that of Oratava, called by Humboldt the finest in the world—are distinguished from barrancos by greater breadth and less precipitous sides, and are not necessarily volcanic in their origin.
The exploration of a barranco is a fruitful occupation. Rare orchids and many ferns spring from between the damp rocks. A shrubby crucifer is occasionally seen on precipitous ledges, and more commonly an equally curious spiny and woolly-leaved composite. The blackberry, which is common in all sorts of localities, here takes on peculiar forms, and leafless suckers thirty feet long swing down the bare cliffs, seeking rooting place.
The bottoms of the watered barrancos and valleys are scenes of tropical luxuriance. The carpet of vivid grass is studded with loose-strife, oxalis, and clover. Wild forget-me-nots love the turf closest to the springs, and our garden nasturtium flings bright-flowered trailers profusely over the banks of the brooks. Maidenhair fronds grow in delicate beauty under the dripping ledges of the rocks. The tiny-flowered speedwell carpets retired nooks, and a species of Lathyrus with large, royal purple blossoms tangles itself around the canes. Here and there are clumps of palm and of native willow, rarely a specimen of the once common Dracæna draco, the famous dragon tree which yields the red gum once so esteemed as a dye and used by the aborigines in embalming their mummies. This tree is by some thought to symbolize the dragon which guarded the golden apples of the Hesperides; for the ancients tried to make old Atlas and his daughters inhabitants of our islands. To moderns this tree is chiefly remarkable on account of its exceedingly slow growth and the very great age which it attains. A specimen at Orotava was estimated by Humboldt and others to be from six thousand to ten thousand years old. This individual was hollow, and had been an object of veneration to the Guanchees since immemorial times; their Spanish conquerors turned it into a chapel. It was blown down in 1868, but
numerous existing trees of much smaller size are still held to have an age of from two thousand to four thousand years.
There is an oak which seems to be thoroughly naturalized in a few places, and a silver-leaved poplar has monopolized whole valley sides. Near the aqueducts and brooks buttercups, vetches, flax, clover, catchfly, sweet clover, sorrel, and plantago abound. In the drier barrancos grows an acacia with globular, orange-colored balls of sweet-scented flowers, also a native sage and the tamarisk tree, with an occasional sturdy castor-oil plant. Very rarely one is fortunate enough to meet with a specimen of a species of juniper formerly forming great woods, now almost extinct on the islands. The cultivated fields and the roadsides have a flora of their own. Among the beans planted as fodder, the white-flowered sweet pea grows luxuriantly, sweetening the air. Vetches, geraniums, morning-glories, larkspur, poppies, and other highly colored flowers rush into bloom on the first approach of spring, making the fields look like veritable gardens of the gods. The roadsides and hills and neglected fields produce numerous gorgeously colored yellow, purple, and red
thistles, of a great variety of genera, very beautiful to look at, when one has not been trying to pick them.
Some plants which have been introduced for cultivation have become partly or completely naturalized. The aloe, which we know as the "century plant," makes hedges along the pathways, and is planted up the mountain sides in rows. It is used as fodder for goats and as thatch for peasant houses, and from the fiber are made baskets, mats, and fish cords. The flower stalks shoot up to a height of fifteen to twenty feet in an incredibly short time, and like mammoth candelabra, as they look, are a striking feature of the landscape. The graceful pepper tree, commonly planted along the highroads, seems to be wild in a few localities. Large groves of magnificent chestnut trees are found on Canary and Teneriffe. The fruit is gathered and sold in great quantities. The almond industry also flourishes in certain regions, and the beautiful trees cover the valleys of a most charming part of central Grand Canary. Fig trees were introduced by some of the earliest European adventurers, and have now become thoroughly established, their fruit being one of the staple foods of the islanders. Oranges and bananas, the chief exports of the country, only grow when planted. Tomatoes, the third great product, are occasionally wild.But the collector's richest fields are the forests. It is impossible to picture to one's self the paradise these islands must have been before the conquering Spaniard wantonly destroyed so much of the woodland. Fuerteventura and Lanzarote are now entirely destitute of native trees, and with the trees went many precious springs, so that these two islands are now practically desert. The chaplains of Béthencourt, who were in Fuerteventura early in the fifteenth century (1402), describe it as "covered with rich vegetation; lentiscos, olives, date palms, tamarisks, and cardos (Euphorbia canariensis) made dense woods," and as having numerous brooks and abounding in herbs and plants and fragrant flowers, which gave to the island a charming and agreeable aspect. Pedro Gomez Escudero, writing of Canaria in the same century, says: "The whole island was a garden, all covered with palms; because from one place, which is called Tamarasaite, we took more than sixty thousand little palms, and from other parts an infinite number." And Dr. Chil says: "After the conquerors and their descendants had for more than three hundred years declared war to the death against the forests, yet at the beginning of this century many leagues were so covered with dense woods that, in going from Telde to San Lorenzo, one arrived in this latter village after a summer day's journey without having seen a ray of sunlight, having passed continually beneath a copious foliage where plants grew perennially fresh and luxuriant." These incontestable facts seem hardly credible, for one would need an abiding supply of scientific enthusiasm now to stay long enough among the scorched rocks of Fuerteventura to make the careful study of their life which is needed. Hierro and Palma are still well wooded, and the extensive forests and abundant water supply of Gomera make it, in Dr. Chil's estimation, the most beautiful member of the archipelago. Only scattered tracts of woodland remain in Canary and Teneriffe.
Tafira, Grand Canary. The hill in the background is of volcanic ashes and is covered in vineyards; on its left slope are a few specimens of Pinus canariensis.
The native pine is a stately tree with wide-spreading circular crown. Its nearest relatives are Mexican and East Indian species. It still covers large tracts of land, and one may ride for hours over the needle-covered ground where hardly any undergrowth breaks the pleasant monotony of the uniform, soft brown. The Canary tamarisk grows in clumps in the drier barrancos, and is also found in the groves of wild olives, Lentiscus, and Bosea which still exist as remnants of the woods which once covered the hills around Tafira. The wiry stems of a twining asclepiadaceous plant (Periploca) wind around these low trees, sometimes making impassable thickets. There are fine forests in Los Telos and near Firgas in Canary, and still more beautiful and much larger ones in the vicinity of Laguna, Teneriffe. Du Mont d'Urville says of one of these (Agua Garcia) that it recalls perfectly the forests of the isles of the Pacific Ocean and of New Guinea. One may ride all day through the half twilight of the dense woods. There are four native species of laurel, belonging to three genera, which here attain superb size; two species of tree heath, two of holly, a beautiful Prunus, and an arbutus tree whose bright orange fruits resemble miniature oranges. The forest flora has a dense undergrowth of native viburnum, shrubby species of the mint, and umbellifer families. There are brooks and beautiful waterfalls, and on the banks of these ferns grow to a height of from four to seven feet. Around the bushes and trees twine the European ivy, and the curious Canarina, a large-flowered member of the morning-glory family, and Danaë, a plant of the smilax tribe, whose flowers spring from the margins of broad-leaflike stem expansions. One of the loveliest of the forest flowers is a large, pale-violet geranium with anemone-like leaves. But mere enumeration can give no idea of the beauties of these wonderful woodlands. Where there have been forest fires or clearings, a host of weeds spring up which, Berthelot says, gain predominance over one another in a certain definite succession, leading gradually to the reformation of forest.Some of the most curious plants of the island flora have a limited distribution. The crater of Badhama in Canary has one or two species unknown elsewhere. Near the great rock of "Saucillo," a pillar of stone, near the center of the same island, one or two unique species have been found. The great crater of Palma, one of the largest and most perfect in the world, is the cradle and only home of others. Above all, the grand old "Peak" and its circle of surrounding mountains, the Cañadas, have proved most prolific in peculiar forms. More thorough exploration may perhaps extend some of these limited areas, but probably will not contradict the extreme isolation of many species. The careful study of the
The Crater of Bandama, Grand Canary; 900-1,400 feet deep; the bottom is inhabited and cultivated.
- The number of peculiar forms on these two very fertile islands will doubtless be increased when they are more thoroughly studied.