| Gt. Atlas valleys. 455 sp. | Middle Zone, Gt. Atlas. 341sp. | Superior Zone, Gt. Atlas. 176sp. | Sierra Nevada, &c., above 800m. 890 sp. | Superior[1]Zone, Sierra Nevada. 486 sp. | Bulgardagh. 882 sp. | Dalmatia. 2,002 sp. | Southern side of the Alps. 2,545sp. | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dicotyledones | 391 | 86·0 | 286 | 83·9 | 154 | 87·5 | 762 | 85·6 | 419 | 86·2 | 808 | 91·6 | 1594 | 79·6 | 2035 | 80·0 |
| Monocotyledones | 64 | 14·0 | 55 | 16·1 | 22 | 12·5 | 128 | 14·4 | 67 | 13·8 | 74 | 8·4 | 408 | 20·4 | 510 | 20·0 |
| Compositæ | 63 | 13·8 | 46 | 13·5 | 22 | 12·5 | 119 | 13·4 | 63 | 13·0 | 97 | 11·0 | 235 | 11·7 | 343 | 13·5 |
| Leguminosæ | 48 | 10·5 | 38 | 11·1 | 14 | 8·0 | 67 | 7·5 | 32 | 6·6 | 93 | 10·5 | 222 | 11·1 | 172 | 6·8 |
| Gramineæ | 39 | 8·6 | 37 | 10·8 | 14 | 8·0 | 59 | 6·6 | 37 | 7·6 | 38 | 4·3 | 173 | 8·6 | 176 | 6·9 |
| Caryophylleæ | 26 | 5·7 | 14 | 4·1 | 15 | 8·5 | 40 | 4·5 | 29 | 6·0 | 81 | 9·2 | 74 | 3·7 | 121 | 4·8 |
| Cruciferæ | 25 | 5·5 | 7 | 2·1 | 21 | 11·9 | 49 | 5·5 | 37 | 7·6 | 84 | 9·5 | 98 | 4·9 | 139 | 5·5 |
| Labiatæ | 23 | 5·0 | 18 | 5·3 | 11 | 6·3 | 54 | 6·1 | 28 | 5·8 | 67 | 7·0 | 100 | 5·0 | 89 | 3·5 |
| Scrophularineæ | 21 | 4·6 | 13 | 3·8 | 10 | 5·7 | 37 | 4·2 | 28 | 5·8 | 39 | 4·4 | 66 | 3·3 | 109 | 4·3 |
| Umbelliferæ | 20 | 4·4 | 16 | 4·7 | 5 | 2·8 | 50 | 5·6 | 23 | 4·7 | 33 | 3·7 | 113 | 5·6 | 113 | 4·4 |
| Rubiaceaæ | 18 | 4·0 | 15 | 4·4 | 7 | 4·0 | 20 | 2·2 | 12 | 2·5 | 19 | 2·2 | 26 | 1·3 | 34 | 1·3 |
| Papaveraceæ | 10 | 2·2 | 8 | 2·3 | 3 | 1·7 | 10 | 1·1 | 6 | 1·2 | 12 | 1·4 | 14 | 0·7 | 14 | 0·6 |
| Geraniaceaæ | 10 | 2·2 | 8 | 2·3 | 4 | 2·3 | 10 | 1·1 | 6 | 1·2 | 6 | 0·7 | 17 | 0·8 | 23 | 0·9 |
| Liliaceæ | 10 | 2·2 | 6 | 1·8 | 4 | 2·3 | 15 | 1·7 | 9 | 1·9 | 23 | 2·6 | 61 | 3·0 | 52 | 2·0 |
| Boragineæ | 9 | 2·0 | 5 | 1·5 | 6 | 3·4 | 18 | 2·0 | 11 | 2·3 | 23 | 2·6 | 40 | 2·0 | 39 | 1·5 |
| Ranunculaceæ | 8 | 1·8 | 5 | 1·5 | 4 | 2·3 | 28 | 3·1 | 15 | 3·1 | 11 | 1·2 | 53 | 2·6 | 87 | 3·4 |
| Cistineæ | 7 | 1·5 | 6 | 1·8 | 1 | 0·6 | 23 | 2·6 | 10 | 2·1 | 1 | 0·1 | 11 | 0·5 | 10 | 0·4 |
| Rosaceæ | 7 | 1·5 | 4 | 1·2 | 3 | 1·7 | 26 | 2·6 | 20 | 4·1 | 21 | 2·4 | 57 | 2·8 | 93 | 3·7 |
| Campanulaceæ | 6 | 1·3 | 5 | 1·5 | 1 | 0·6 | 9 | 1·0 | 6 | 1·2 | 21 | 2·4 | 26 | 1·3 | 46 | 1·8 |
| Convolvulaceæ | 5 | 1·1 | 5 | 1·5 | 1 | 0·6 | 3 | 0·3 | 2 | 0·1 | 4 | 0·5 | 10 | 0·5 | 9 | 0·4 |
| Coniferæ | 5 | 1·1 | 4 | 1·2 | 1 | 0·6 | 10 | 1·1 | 8 | 1·6 | 15 | 1·7 | 15 | 0·7 | 11 | 0·4 |
| Saxifrageæ (inclusive of Grossulariæ) | 4 | 0·9 | 4 | 1·2 | 4 | 2·3 | 12 | 1·3 | 9 | 1·9 | 2 | 0·2 | 9 | 0·4 | 52 | 2·0 |
| Cyperaceæ | 4 | 0·9 | 4 | 1·2 | 1 | 0·6 | 17 | 1·9 | 12 | 2·5 | 7 | 0·8 | 43 | 2·2 | 119 | 4·7 |
| Gentianeæ | 0 | 0 | 0 | 0 | 0 | 0 | 7 | 0·8 | 5 | 1·0 | 4 | 0·5 | 14 | 0·07 | 31 | 1·2 |
| Primulaceæ | 2 | 0·4 | 2 | 0·6 | 1 | 0·6 | 7 | 0·8 | 6 | 1·2 | 8 | 0·9 | 12 | 0·6 | 60 | 2·4 |
| Junceæ | 1 | 0·2 | 1 | 0·3 | 0 | 0 | 11 | 1·2 | 9 | 1·9 | 0 | 0 | 8 | 0·4 | 31 | 1·2 |
the whole number of phanerogamous species included in the Flora of the region, and opposite the name of each natural order I have entered the number of species found in each region, and the percentage proportion which this number bears to the entire flora. Besides the orders which bear the largest proportion in the Great Atlas Flora I have enumerated those that usually characterise the vegetation of high mountains in this part of the world, though several of these are little, or not at all, represented in the Flora of the Great Atlas.
Confining the comparison in the first instance to the figures given for the Atlas Flora as a whole in the first column, and those given in the fourth, sixth, seventh, and eighth columns respectively, for the Sierra Nevada, the Bulgardagh, Dalmatia, and the southern side of the Alps, we remark in the first place that Monocotyledons bear about the same proportion to Dicotyledons in the Great Atlas that they do in the Sierra Nevada, the percentage here being much larger than it is in the Bulgardagh, and considerably less than in Dalmatia or the Southern Alps. In this part of the world this percentage in the Flora of a given region mainly depends upon the number of Gramineæ and Cyperaceæ. The abundance of the latter group in the Alps doubtless arises from the fact that at a former period physical conditions favoured the migration of a large number of northern species that have been unable to extend to the more southern mountain regions of the Mediterranean area.
In all the regions under consideration we find, with a single exception, that the same eight natural orders take precedence of all others as regards the number of species that they exhibit, the aggregate in every case exceeding one-half of the whole phanerogamous Flora. These natural orders are Compositæ, Leguminosæ, Gramineæ, Caryophylleæ, Cruciferæ, Labiatæ, Scrophularineæ, and Umbelliferæ. The exception arises from the prevalence, already noticed, of Cyperaceceæ in the Flora of the Southern Alps. In comparing the figures in the Great Atlas column with those for the other areas above enumerated, it is well to recollect that our materials are taken from a district much more limited in extent than the others, and are necessarily imperfect, because obtained from a single short visit to each valley at a season when many species are yet undeveloped. It is probable, for instance, that the proportion of Umbelliferæ would be increased if the whole Flora were better known. Subject to this remark, it will be seen, as might be expected, that the constituents of the Great Atlas Flora show more analogy with those of the Sierra Nevada and Bulgardagh Floras than with those of Dalmatia and the Southern Alps; but the proportion of Compositæ is larger than in any of them (nearly 14 per cent). In comparing the vegetation of a small district with that of a large one it must be recollected that a small natural group containing a few widely spread species, such as Geraniaceæ, is likely to show a larger percentage proportion to the whole Flora in the small district than in the larger one. It may happen that the same species are spread through both regions; but in one case the number is to be compared with a small total, in the other with a much larger one. This remark has a bearing on the fact that in the Great Atlas Flora the natural orders that bear an unusually large proportion to the total number of the Flora are Leguminosæ, Caryophylleæ, Rubiaceceæ, Papaveraceæ, Geraniaceæ, and Convolvulaceæ. On the other hand, there is a remarkable deficiency in the natural orders that especially characterise the Flora of the Alps, and in a less degree, the high mountains of Southern Europe. These are Ranunculaceceæ, Rosaceæ, Saxifrageæ, Primulaceæ, Junceæ, and Cyperaceæ; not to speak of Gentianeæ, which are here altogether absent.
If, instead of regarding the Atlas Flora as a whole, we examine separately the figures given in the several columns for the middle and superior zones respectively, we find very different proportions for the chief natural orders, except for Compositæ and Leguminosæ which are in both very numerous. In the middle region of the Atlas these two orders represent very nearly one-fourth of the phænogamous Flora. After these Gramineæ, Rubiaceæ, Papaveraceæ, Geraniaceæ, Cistineæ, and Convolvulaceæ are, in the middle region, unusually frequent, while Cruciferæ, Rosaceæ, Boragineæ, and Liliaceæ are remarkably deficient. In the superior zone, on the other hand, the proportion of Compositæ and Leguminosæ is less excessive, making jointly a little over one-fifth of the whole Flora of the upper region. The most marked characteristic here is the very large proportion of Cruciferæ, being less by one species only than the number of Compositæ. Taking into account the number of individuals as well as that of species, this must be regarded as the dominant element in the Flora of the higher region of the Great Atlas, affording as it does 12 per cent of the whole Flora. The only region in which this characteristic is approached is the Bulgardagh in Cilicia, where Cruciferæ supply near one-tenth of the whole list. Caryophylleæ also form an unusually large element in the Flora of the upper zone of the Atlas; but, unlike Cruciferæ, this order exhibits no endemic species, and four-fifths of the whole number are common plants of Central and Northern Europe. Rubiaceæ and Boragineæ have more representative species than is usual in mountain Floras; while there are but three species of Rosaceæ in our list; and Campanulaceæ, Primulaceæ, Coniferæ, and Cyperaceæ are each represented by a single species, and Gentianeæ and Junceæ are altogether absent from the higher zone.
Although statistical results, such as those given above, are not without interest, as throwing light upon the general characteristics of the Flora of a given region, any rational grounds for speculation as to the real affinities and past history of the vegetation must be derived from a closer examination of the individual species of which it is constituted. It is at least conceivable that two Floras should exhibit similar proportions of species belonging to the several natural groups, with no identical species, and with little or no indication of community of origin. The particulars given in our general list will have already led the reader to infer that the results of an examination into the distribution of the individual species that go to make up the Great Atlas exhibit some very peculiar features. Taking the totals at the foot of our list, and excluding cryptogams, it is seen that more than one-third of the species are plants of Middle and Northern Europe, while about one-sixth is made up of endemic species peculiar to Marocco, and, with few exceptions, not known out of the Great Atlas, more than half of the whole list belonging to one or other of these categories. The results, as shown in the following table, are still more remarkable when we separately examine the zones into which mountain vegetation is naturally divided. As in the former table the figures first entered in each column represent the number of species belonging to each category, those next given showing the percentage proportion borne by that number to the total proportion of each region.
Table II.—Showing the distribution of the species of flowering plants included in the Flora of the Great Atlas, and of the Sierra Nevada of Granada,[2] and the Bulgardagh in Cilicia.[3]
| Mid-European | Wide-spread Mediterranean | Confined to adjoining regions | Endemic | |||||
|---|---|---|---|---|---|---|---|---|
| Great Atlas, including all species found above1,200 m. 455 sp. | 154 | 33·8 | 165 | 36·2 | 61 | 13·4 | 75 | 16·6 |
| Middle Zone of Atlas, from 1,200 m. to 2,000 m.341 sp. | 106 | 31·1 | 141 | 41·3 | 46 | 13·5 | 48 | 14·1 |
| Superior Zone of Atlas, from 2,000 m. to 3,500 m.176 sp. | 78 | 44·3 | 43 | 24·4 | 20 | 11·4 | 35 | 19·9 |
| Superior Zone of Sierra Nevada, above 1,600 m.486 sp. | 209 | 43·0 | 74 | 15·2 | 104 | 21·4 | 99 | 20·4 |
| Bulgardagh in Cilicia. 882 sp. | 159 | 18·0 | 359 | 40·7 | 157 | 17·8 | 207 | 23·5 |
From this table we see that while over one-third of the whole Atlas Flora consists of plants of Central and Northern Europe, the proportion reaches nearly to one-half in the higher region (above 2,000 metres); and also that the proportion of endemic species, which in the aggregate is one-sixth of the whole, rises to one-fifth in the upper zone. On the other hand, the proportion of purely Mediterranean species, which amounts to 55 per cent. in the Flora of the middle zone, falls below 36 per cent. in the upper region. Of these Mediterranean species the large majority (more than two-thirds) are widely distributed plants, several of them extending to the mountains of Asia Minor, and twenty species only are exclusively confined to the Great Atlas and to the mountains of Southern Spain, the Lesser Atlas, or the Pyrenees. There is nothing in the distribution of these latter plants to indicate any special connection between the Atlas and any one of the mountain regions above mentioned. Six Atlas species are common to Southern Spain and the Algerian Atlas, six more are known only on the mountains of Southern Spain, five have been hitherto supposed to be peculiar to the Lesser Atlas, and three are elsewhere confined to the Pyrenees.
Some further light may be thrown on the origin of the Great Atlas Flora by considering the affinities of the plants which are reckoned in our list as endemic in Marocco, nearly all being confined, so far as we know, to the chain of the Great Atlas. Although all of these, along with some that we have classed as mere varieties, would be counted as distinct species by many botanists, a considerable number, amounting to more than a quarter of the whole, are, according to the views expressed elsewhere by the writer,[4] to be ranked as sub-species. But here again we fail to discover indications of special relations between the Great Atlas Flora and that of neighbouring mountain regions. Ranking as sub-species twenty-one out of the seventy-five endemic forms enumerated in our list, we find that ten of these are allied to widely spread Mediterranean species, three are related to plants of Central Europe, three to species common to Algeria and Southern Spain, three more to species confined to the Spanish peninsula, and two to endemic Algerian forms.