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.

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 this—that, 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 Śnos; 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.

Journal of the Royal Horticultural Society (1847)
XI. On Hybridization amongst Vegetables. Part the Second.
Hon. and Very Rev. William Herbert, LL.D., F.H.S., Dean of Manchester.
Crocus, pp. 82-84

The genus Crocus, with great uniformity of aspect, branches into an infinity of species and local varieties, being found in peculiar situations and soil, but with greater similarity of habits and constitution than Crinum; and it might have been supposed that, when brought into cultivation, their seminal produce would become confounded. On the contrary, I have tried in vain for years to obtain any cross; I have not one as yet on which I depend; and, if I have any, not above three or four such bulbs, and about as many seeds. The cross-impregnation seldom produced a pod, and, if it did, the seed was usually shrivelled and bad. Look at the geological map of Bory St. Vincent. Half the island of Milo consists of igneous rock, half of marble and schist. On the schist he found C. laevigatus. The same schist appears in Thermia; C. laevigatus is there. I know that it passes thence to Hymettus and to the neighbourhood of the quarantine station at Zeitun. I doubt not that a like calcareous formation will be found there. But why does C. laevigatus jump from the summit of Milo to the summit of Thermia, and thence by Hymettus to Zeitun, without touching the hills of Epidaurus or Nauplia, or any part of the Moraea, as far as it has been searched? I believe because the soil, subsoil, and climate, in which it grows, have forced Crocus to take that form and aspect which botanists call C. laevigatus, not that it has a predilection for such, for experience leads me to think that few local bulbs or even plants prefer their native soil, though they are found in it because they can endure it, while the rivals, which would otherwise oppress them, cannot thrive vigorously in it. Many such are found to perish if potted or cultivated in their native soil removed to another situation, finding either an injurious increase or diminution of moisture in the new position, which makes a different soil expedient for them there. Griffinia grows in mountain woods in very strong loam; it will scarcely live in such soil in our stoves, where it seems to like sandy peat. Ismene Amancaes grows in Bolivia in loam strong enough to break an iron crow; here it must be cultivated in pure white sand. I find such European Orchideae and Croci as grow in chalky or calcareous stuff, very much disposed to canker and die if potted in the like, while the fresh tubers and corms of almost every kind turn out well from a yellowish crumbling loam of moderate tenacity. No Crocus grows naturally in alluvial soil, probably because other plants would there smother it; but many, if not all, delight in it in a sufficiently dry situation, when cultivated. Different soils, therefore, suit the same vegetable under different circumstances, because in different positions they will have to contend with other difficulties and other rivals for the occupation of the soil. I consider a due quantity of moisture, without excess or deficiency, to be the main requisite to every plant which has peculiar local affections, premising that it must have space, unincumbered by stronger rivals that would over power it, and a suitable temperature. I have found a blue Statice growing aloft in solid stone at the back of Portland island, and elsewhere on the brink of a runnel in a saltmarsh; I have found Gentiana verna on the firm turfy brow of the St. Gothard, and in the flooded marshes at the head of the lake of Thun. The clouds and the sea-spray and fog furnished in the high position that incessant moisture which those plants demanded, and which the rival grasses found to be superabundant for their use and injurious to their vigorous growth.

To return to C. laevigatus: one of two views must be adopted, either that schist, in a position where it receives a certain degree of moisture under a certain temperature, is essential to enable a variation of the genus Crocus which originated in such a position to reproduce and maintain itself against all intrusion, or that the like data tend to produce a similar variation in different insulated spots; but it is not easy to suggest a satisfactory reason why such an indisposition to intermix should exist in a genus which branches into so many local species with so much general conformity both of habit and aspect. It has sometimes occurred to me, that the variations produced by circumstances of poverty, where the plant exists by superior powers of endurance, become more fixed than those which arise from luxuriance. Crocus seems to me to live in a state of constant mountain warfare, avoiding the presence of powerful rivals; Narcissi shoot both early and vigorously, and usually domineer over the grasses, &c., in the position they choose. The attempt to cross Crocus vernus with other species led to some interesting observations. Plants thereof were taken up and potted at the flowering season for that purpose. I found that no excision, however deep, of a flower that had expanded itself, and of which the pollen was set free before it was taken up, could prevent the underground germen within the sheaths of the plant from perfecting its seed in due time. The fertilization had taken place and could not be arrested. On the other hand, no application of its own pollen would fertilize a flower after the transplantation; the check received prevented the fertilization; prevented, as I believe, the plant from supplying that which the pollen required to enable it to elongate its tubes. But a further remarkable circumstance was observed. The roots so potted were plunged in a sand-bed, that they might be ready for the next year's operation without transplantation; but two seasons succeeded, and those roots produced no flower. A small bulb of a variety of C. vernus from the Splugen had been also potted two years, and did not flower. It was planted out, and no longer failed. What does this imply? I suspect that the relative cold and moisture of the crown and the base or fibres of a plant is an important point which cultivators have overlooked, and which may be one of the agents by which local variations have been produced. C. vernus on the Alps, at an elevation of 5000 feet, frequently flowers by piercing the yet unmelted remnant of snow. In that position its head is wet and very cold, while its tail descends to the warmer and drier stone. In a pot at my window the vernal sun warms its head, while the pot detains the wet round its fibres and the evaporation from the pot chills them. The relative circumstances are therefore reversed. When I find that Crocus vernus does not descend below 5000 feet on the mountains of the South of Italy, and that its near kin C. Imperatonius flourishes there between 2000 and 8000 feet above the sea, I cannot avoid suspecting that the variation was worked in times by-gone by the difference of position, and I ask myself whether the different relative moisture and warmth of the two extremities of the plants, and not the mere difference of soil and temperature, caused their diversity, and now prevent their juices from co-operating for mutual fertilization.