Comparison of the Maroccan Flora with that of the Mountains of Tropical Africa.

By Joseph Dalton Hooker.

As was to have been anticipated, the Maroccan Flora contains most of the European species which have been collected on the mountains of Abyssinia and of the Bight of Biafra, which alone of the tropical African Alps have been botanically explored. Of these the former have been visited by Schimper and various collectors; whilst the mountains of the pestilential West African coast, of Fernando Po, 9,500 feet, and the Cameroons Mountains, upwards of 13,000 feet, have been ascended for botanical purposes only by Gustav Mann, when employed for the Royal Gardens of Kew.

The results of the latter were published by myself in the ‘Journal of the Linnæan Society of London’ (vol. vii. p. 171), from whence the following observations are for the most part extracted. They included 26 European species, gathered at elevations between 5,000 and 10,000 feet. Most of them are also natives of the Abyssinian Alps, and two-thirds of them are also Maroccan, whilst others will probably yet be found in the latter country.

The following is a catalogue of all the European plants found in the upper regions of the Cameroons Mountains and Fernando Po:—

The most remarkable features of the Temperate vegetation of these West African tropical mountains are:—

1. Its poverty.

2. The preponderance of Abyssinian genera and species.

3. The considerable proportion of European plants.

4. The paucity of South African genera and species.

5. The great rarity of new genera.

6. The absence of St. Helena and Canarian types.

Upon each of these propositions I have a few general remarks to offer.

In the poverty of their Flora the Cameroons range and Peak of Fernando Po seem to partake of the characteristics of the Abyssinian Alps. We know far too little of the physical geography of either of these districts to hazard many conjectures upon this point, which must to a certain extent be dependent on the arid volcanic nature of the soil and the limited area of the Temperate region. Mr. Mann spent many weeks, and at various seasons, in his explorations, and yet 237 flowering plants were all that rewarded his toil. Geological causes have probably had, in the case of the Cameroons Mountains, much to do with the dearth of species, some parts of the range even now presenting evidence of subterranean heat.

The preponderance of Abyssinian forms is proved by almost all of the genera and half the species being natives of Abyssinia, and by many other species being very closely related to, or obvious representatives of, plants of that country. There are, further, several of the genera and many of the species peculiar to Abyssinia and the peaks of Biafra.

The number of European genera amounts to 43, and species to 26, the greater part of which are British. Very few of them extend into South Africa. The greater part are Abyssinian; the remarkable exceptions being Radiola, Scabiosa succisa, Luzula campestris, and Festuca gigantea, all of which, however, may have been hitherto overlooked in Abyssinia.

I find no other evidence of relationship between the Biafran mountain Flora and that of Marocco than what is afforded by the European species common to both. In most other respects the Floras differ totally, the other mountain plants of Biafra being Abyssinian or Cape types, or more nearly related to tropical African ones.

On the Mountain Flora of Two Valleys in the Great Atlas of Marocco.

By John Ball.

Although an attempt to discuss the character and relations of the Flora of a region so wide and so little known as the mountain region of the Great Atlas would as yet be quite premature, it appears that the materials at our disposal suffice for an examination of the vegetation of the valleys lying south and south-west of the city of Marocco, which may be an acceptable contribution to botanical geography. For this purpose it seems best to limit the discussion to the two valleys where our collections were sufficiently extensive to give a tolerably complete representation of the vegetation, as far as this was developed at the season of our visit, and to exclude altogether the plants found along the skirts of the great range below the level of about 1,200 metres above the sea. The Flora of the zone below that level is largely mixed up with extraneous elements, represented by plants of the low country that reach the base of the mountains, but do not penetrate the interior valleys, and if these had been admitted the special features of the mountain Flora would have become less apparent. The plants collected in the course of a somewhat hurried excursion from Seksaoua, when we reached a height of about 1,600 metres, have been designedly omitted. On such occasions attention is to a great extent monopolised by the new and rare species not hitherto seen in the same region, while comparatively familiar forms are less carefully noted. Collections made under such circumstances rarely give a moderately complete report of the vegetable population.

In ascending to the higher region of mountains that approach to the limit of vegetation the absolute number of species is so much smaller that this source of error is far less apparent; and it is not likely that in the two ascents which we made to the dividing ridge of the Atlas many species that came within our range of vision were overlooked. The following tabular arrangement shows that in the Aït Mesan valley, where we spent the greater part of six days, we collected 375 species of phænogamous plants, to which have been added three subsequently found there by MM. Rein and Fritsch; while in the Amsmiz valley only 223 species—or less than three-fifths of the above number—were collected. Of these 146 species are common to both valleys; so that our list does not in all exceed 455 species of flowering plants, to which I have added 10 vascular cryptogams, of which two only were found in the Amsmiz valley.

In the following list I distinguish a middle zone, extending from 1,200 to 2,000 metres above the sea, and a superior zone including all above that limit; the latter corresponding pretty nearly with the sub-alpine and alpine zones of the higher mountains of Europe. With reference to their distribution I have divided the species into four categories: 1, Mid-European, those extending to Central Europe, of which more than three-fourths belong to the British Flora: 2, wide-spread Mediterranean, extending beyond the bounds of the three adjoining regions, Algeria, the Spanish peninsula, and the Canary Islands: 3, confined to adjoining regions; that is, to one or more of those just enumerated: 4, endemic, known only in the Great Atlas, or the neighbouring provinces of Marocco.

Tabular View of the Mountain Flora of the Great Atlas, showing the distribution of the Species found in the Valleys of Aït Mesan and Amsmiz. S indicates the superior zone from 2,000 m. to 3,500 m. above the sea; M the middle (or mountain) zone, from 1,200 m. to 2,000 m.