Page 2 - Francini_Messeri_2013

The gariga: some typical communities of which are chiefly composed by Satureja
fruticulosa var. caespitulosa and HeUchrysum pend/ulum and grow on the steep east slopes of the
island (North of the village), accompanied by a residual group of Pinus halepensis, localized in one
station. This gariga can be considered as a mountain type of vegetation.

The endemic plants (Scabiosa limonifolia, Bupleurum dianthifoUum, Scilla Hughii, Brassica,
macrocarpa) and the most peculiar ones (Dianthus rupicola, Seeeli Bocconi, Iberis semperflorens)
find their only habitat on the vertical cliffs with North-North-East exposure, where they grow
luxuriantly.

A particular study of the most important plants of this flora is presented here. This research has
been performed from a chorological and anatomical-ecological point of view as well as by means of
the valuation of its degree of specialisation to the habitat of vertical cliffs, in order to reconstruct the
history of the plant population in the island.

This study led us to assume that the most peculiar flora of the island consists of plants characteristic
of tropical-subtropical mountains, where the widest climatic oscillations take place during the day
and not during the year (diurnal climate instead of a seasonal one).

The ecological categories in which the rare plants of Marettimo can be classified are as follows:

1. Shrubs of evergreen mesophilous type (Figg. 62, 76, 78) probably originated at a low
mountain altitude, characterized by a high atmospheric humidity and fog during a part of the
day.
The most typical representatives (Bupleurum dianthifolium, Dianthus rupicola, SeseK
Bocconi) are localized to peculiar habitats, probably from a remote geological period
(presumably before the end of the Miocene) and show adaptation to the vertical cliffs which
exceeds the most accentuated preadaptation.
It is presumed that from this ecological type might have taken origin the evergreen shrubs,
expecially of sclerophyllous type, of the mediterranean macchia of today. These plants might
have kept some of their original morphological features (scarse conducting power of the
wood tissue, general leaf shape) and changed deeply some others (introduction of definite
resting periods in the growing process, change of leaf structure from mesophilous to
xerophilous type). We find in Scabiosa limonifolia (Figs. 69, 92, 95) a good example of a
plant in which the mediterranean features have been reached only in part. According with
this incomplete evolution the plant has not been able to spread like the true mediterranean
ones, but survives today as a relict on the vertical rocks. Much likely in the same way
behaves a mesophilous ecotype of Lonicera implexa (Figs. 107, 108), exclusively bound to
the peculiar habitat of the vertical cliffs, for which, being a liane, is well pre- adapted. To the
same group belongs Iberis semper flor ens, which shows the same general characteristics
as Buplevrum dianthifolium, Dianihus rupicola and Seseli Bocconi, but has a greater
tolerance for xerophilous habitats and no adaptation to the vertical cliffs, while it is well
preadapted for this habitat.
The origin of these plants must be sought for up to the paleogene in the mountains of the
mediterranean district, under a tropical climate.
These plants show some differences one from the other, owing to the place and time of their
origin:
Bupleurum dianthifolium whose origin might be brought back to the Betic-Riffan land, in the
Western Mediterranean, is the most mesophilous and strictly localized; Seseli Bocconi which
could have taken origin in the Corsardinian lands is less mesophilous and less severely
localized; Dianthus rupicola of the Egean Continent, besides its mesophüous characters,
shows also some other characteristics which let it spread over a rather large area.