Journal of the Horticultural Society (1846) 44-49
V.Local Habitation and Wants of Plants.
By the Hon. and Very Rev. William Herbert, F.H.S., Dean of Manchester.
(Communicated November 17, 1845.)
Cephalanthera rubra (otherwise called Serapias rubra) is said to grow in the woods of Ingleborough, in Yorkshire, and I once saw a weak specimen of it without flower in the neighbourhood of Hampton Common, in Gloucestershire. While I was in the neighbourhood of Thun I learnt that this plant, of which I had as yet seen nothing in my rambles amongst the woods in the mountains near the lake, inhabited a large wood further from the town. I was desirous of seeing it in its native place, with a view to observe what the circumstances were that caused it to be so rare and confined to peculiar localities. I therefore proceeded along the edge of the beautiful lake till I found myself opposite to the commencement of the wood that had been pointed out to me. It was very extensive, densely timbered, and exceedingly steep, the lower part of the declivity being occupied by meads and vineyards. It was evident that without some clue to discover the precise habitation of the plant I wished to find, I might, after a long scramble through a wood that was nearly precipitous, return home without having seen it. Looking therefore to the nature of the ground, it occurred to me that, if it grew under such thick shade in so steep a position, it would probably prefer the neighbourhood of some channel along which the rain-water rushed down from the mountain. I determined therefore to attack the wood at that point, and, entering the dry and stony water-course by which the thunder-storm of the previous evening had hurried down its torrent to the lake, I followed it till I reached the border of the wood; and entering it, I had not advanced two steps before I saw three plants of Cephalanthera rubra, weak and without flower, in the channel, and growing from under some round stones washed down from the conglomerate above. The groove was here very deep, and its sides, on the right and left, too steep to be climbed without laying hold of the roots or boughs. I made my way however to the top of it, and proceeded some way along the brow and sides without seeing any orchidaceous plant, except the butterfly orchis. Thereupon I descended again to the bottom of the ravine, where I immediately found the Cephalanthera abundant, but weak, growing in a mixture of sand and rotten leaves under the round stones. Following the water-course upwards I continued to find it; and at last, on an angle of a stronger yellow earth, at the junction of two water-courses, I found the plant more abundant, stronger, and just coming into flower.
It seemed that this plant likes dense shade, not upon a northern slope, but in an aspect which lets in a checkering of sunshine; that it requires the heavy coat of dead beech-leaves to be washed away by waters, and its roots to be frequently refreshed by the great body of water that runs down after every heavy rain, but does not. remain and stagnate on the ground. The dead stems of last year were still adhering to the plants, and I did not see a single specimen with two stalks either of the present or of the last year. At the foot of each stalk, where it joined the fibrous roots, was a single eye for the next year's shoot. With this knowledge of the plant's habits (if those which I brought home survive the transplantation and journey in the season of their growth, so as to sprout again) I should hope to be able to cultivate them.
I had previously observed that Cypripedium Calceolus, growing in open grassy spots on the steepest knolls in the woods, was in its glory on the brow of a deep ravine, through which a strong and constant stream of water ran down, which after heavy rains would be greatly swollen. The earth seemed also to be moistened by water from above, unable to penetrate the rock underneath, and occasionally bursting out through the soil. It is evident to me, that mountain-plants require much moisture, and that drought is their principal enemy in cultivation.
I observed Gentiana verna flourishing on the southern brow of the San Gothard Alp, where the clouds must often rest: I next saw it more vigorous in the marshes between the lakes of Thun and Brienz, where water was absolutely standing, in company with Primula farinosa and Orchis latifolia, both notoriously swamp plants; the former of which flowered most profusely when absolutely in the water of a ditch. I afterwards observed Gentiana verna, not less healthy, with Pinguicula vulgaris, in such a hill-side bog near Thun as a jack-snipe is apt to select for his residence.
Orchis (or Herminium) Monorchis is found in England on slopes of chalk and stonebrash. I met with it in the reed-beds close to the edge of the lake of Brienz, in company with Epipactis (or Serapias) palustris; and I also saw one vigorous plant of Orchis militaris, which is reputed to grow only on dry chalk, in the same marsh; and three in a flat, half' flooded meadow near the sea, a few miles from Trieste.
These observations lead me on to a question which has often suggested itself to me, "Why do plants, which are found only in particular situations, improve under cultivation, and (as I believe to be the case) more so than those which are generally dispersed?" and, consequently, "Is the soil or subsoil, on which alone certain plants are found in a wild state, necessary to them, or at least always best for them?" I think the answers must be "No" to the latter question; and to the former question, "Because their most dangerous rivals, which in a wild state would overpower them, in richer soil are removed;" and that in truth the weaker plants in many cases are peculiar to those soils which are not best for them, but where they can exist, and where the grass and other enemies cannot grow with sufficient strength to choke them.
I found Crocus variegatus on the Carso of the mountains behind Trieste, where the grass is so meagre that the grey stones look through it; but there a very small proportion of the bulbs bear flowers, and still fewer yield seed. The crocuses of the Ionian Islands are in the same manner dispersed amongst the rocks and stones of the mountains, where there is scarcely any grass, and in the spots where the cistus and other mountain-shrubs do not overpower them; but they flower and fruit very sparingly, and the bulbs are very small and weak: and the same I understand to be the case on the Alps of Trebizond, where, as well as on Bithynian Olympus, the bulbs are curiously diminutive from the poverty of the soil and bleakness of the position. On Mount Roudi, in Cephalonia, the greater part of those I saw were perishing from a murrain which seemed to have been induced by very wet weather in February and March. Yet crocuses brought from calcareous mountains into the garden of a Dutch florist, and severed from their native soil, acquire tenfold vigour and size of bulb. Few, however, of the crocuses from rocky mountains flower when taken up till they have been one year in cultivation. I apprehend the fact to be thisthat, if the seed of the crocus were to fall in such a goodly heritage without the protection of the weeding-hoe, it would be strangled in its birth by stronger occupants; and that, on the chalk and other calcareous rocks, there are places where few vegetables can exist; while the bulbs of this and some other genera take refuge there and get a poor livelihood in peace and quiet. I saw a Crocus, a Sternebergia, and an Ornithogalum growing in contact with each other aloft on the meagre sod of Mount Œnos; but not a seed-pod of the Sternebergia could be discovered, and very few of the crocus. In a more fertile sod they would have been choked by some stronger plant, but they would rejoice in a better soil, if protected against the oppressor.
The usual habitation of the various species of crocus is on calcareous mountains; and, as such are of various descriptions, they seek a more elevated or a steep position, which is unfavourable to the growth of grass, on those which are most fertile. Some species, however, like more humidity than others; and C. speciosus and Byzantinus, which desire a fertile soil, seek the shade of woods, where the roots of trees perforate the earth and render it looser and drier than it would be otherwise. From the mountains behind Trieste to the south of Greece the soil on which crocus grows becomes gradually redder as we advance, and is intensely so in the neighbourhood of Nauplia: in Negropont it is browner, and on the lofty Veluchi, in Ætolia, slightly ferruginous towards the summit; but the bulbs are more vigorous in detritus of greyish greenstone, on its lower projections and near its base. In all these positions the soil is rather strong, but dry. One only species in the Cyclades is said to grow in sand upon clay.
The compost, in which the Dutch raise their improved bulbs of various kinds, is known to be (see Sismondi, des Jacinthes) a compost of humus, obtained from thoroughly decayed elm-leaves and dung of stall-fed cattle, and mixed with sand deposited by the sea on a bed of prostrate timber of unknown antiquity, in which there is probably nothing calcareous. Does it not then appear that the case stands thusnot that calcareous matter is essential to the growth of crocus, or even a useful auxiliary, but that crocus can bear the sterility of elevated calcareous mountains better than most other plants of stronger growth? If that be true of one genus, it will probably be applicable to others.
Let us proceed from that consideration to more general views. The richest soils, if well moistened, will necessarily be occupied by the vegetables which grow most rapidly, and with such spreading and persistent foliage as to prevent slower but more robust rivals from gradually supplanting them; but that which has sufficient powers of endurance to struggle through, will become the ultimate lord of the forest. Such is, perhaps, the sugar-maple of America, which is said to reign almost exclusively on the best soil. In each successive grade of inferior fertility the like struggle must be maintained, and the power of endurance must finally determine which shall be the occupants of each several position; though the question of endurance will turn upon various points, such as excess or deficiency of light, heat, and moisture, and denseness or lightness of the atmosphere or soil.
The first step in cultivation is therefore the use of the extirpator of intrusive vegetables, whether it be the hand, or the hoe, or the plough and harrow; the second step, after having ascertained whether the plant in its natural state exists by enduring the want or the excess of moisture or heat, will be to relieve it from the necessity of such endurance, as far as it is injurious to its vigorous development. Thus it will be found that Orchis latifolia, removed from the swamp, in which it struggles with other swamp-plants, will grow more vigorously where it is cultivated with less wet. The small Polygala vulgaris is stated in Mr. Babington's Manual to grow in dry pastures, having flowers either blue, white, or red. I believe the stated habitation to be only thus far true, that it does not grow in water. I do not recollect seeing it in sandy pastures: I know it well on chalk and on clay. In England it is little admired. In the alluvial and very moist meadows of Zante, near the sea, in the vicinity of Trieste, it formed a most conspicuous part of the meadow-crop at the end of May, and the beauty with which it painted the herbage was to me astonishing. It seemed that, in a warmer climate, it could endure more moisture than with us. On the slope of Monte Spaccato, where no grass grows, large single plants of it stood in the bare soil amongst the stones, with every intermediate diversity of pearl-colour and lilac, showing evidently that the merits of that little plant under cultivation are not appreciated or known. We must recollect that sandy soil could not abide on very steep hill-sides.
On the San Gothard pass I observed the little yellow violet, of which I had possessed a plant twenty-five years ago that was quickly lost, flowering profusely on the northern face of rocks from which water oozed through every crevice. Sometimes its roots were confined between two horizontal layers of stone, and it flourished all along the crack, in the manner of the small trailing snapdragon; sometimes it grew under an overhanging ledge of rock; but, where the ground amongst the rocks was constantly moistened by a fresh supply of oozing water and the sun did not reach, it luxuriated.
The Pyramidal Saxifrage delights in similar positions, growing often on the bare rock, of which the crumbled particles gathered round its roots, and the were constantly refreshed by the issuing moisture; but it had a wider range than the yellow violet: flourishing in such positions in the narrow valley of the Ticino as well as on the Alps, its graceful blossoms waving in the air, and pendulous, not naturally pyramidal. The rare Saxifraga mutata, which has the same general aspect as to the foliage, with a spike of yellow flowers, was pointed out to me in the neighbourhood of the lake of Thun actually riding on the water of a mountain-brook, with its roots spreading under a large stone in a wide naked space of round and pulverised stones, towards the mouth of the deep ravine along which they had been brought down from the mountain. I was told that I should have no chance of preserving it alive, unless it could be planted immediately. It was therefore tied up in a piece of linen with a handful of the stone-powder in which it grew, and, being kept moist, it reached England alive. Climbing the steep sides of the ravine afterwards, I saw several more of the same species aloft, where the water burst out, and one was growing in a tuft of moss. I pulled up another also, which was near, and, inserting its roots into, the same moss, I tied the moss in the shape of a ball, and they were so brought to England. The first was potted in its native soil, and, having been left three weeks in the care of my gardener, was found to be dead on my return. The moss-ball had been set in the mouth of a pot filled with moss, and placed in a large pan of water. The two plants in it have continued to thrive well, and that which had been pulled out of the ground cannot be distinguished from the original occupier of the moss. The plant was figured about forty years ago in the 'Botanical Magazine,' where it is stated that great care must be taken not to give it much water. It is very possible that in a pot of earth, the wet which is suitable on a rock in moss might cause the fibres to rot, if the drainage were insufficient. I am however satisfied that the difficulty of cultivating Gentiana verna arises merely from its thirstiness, and that it should be planted in a mixture of strong soil with peat, or in a bed of peat on clay. It is said that Epigaea repens, which has been found the most difficult of plants to cultivate, will thrive in a peat-bed of great depth. 1 apprehend that in such case its extreme roots find moisture below when the peat near the surface becomes too dry for it. Probably a less depth of peat would preserve it, if a cup-formed bed of clay were placed under the peat to retain moisture.