A FLORA OF GIBRALTAR AND THE NEIGHBOURHOOD XV 



The latter is sandy, and is now levelled and turfed for recreation 

 where it is not occupied by buildings ; only a small portion near 

 the Devil's Tower and the rifie butts is in anything like its 

 original state. Formerly the North Front was for the most part 

 as wild and rough as the present Neutral Ground, and produced 

 many species now " improved " out of existence, thougli some 

 doubtless survived until Kelaart's time. These will be dealt with 

 more fully under District II. 



The Eock itself is a mass of limestone, sloping towards the 

 west, with the bare rock appearing all over the middle and upper 

 slopes. The backbone of the Eock, which is about two miles long, 

 rises vertically from the North Front to an altitude of 1350 ft. 

 into a sharp ridge from 1000 ft. to 1440 ft. high, extending to 

 O'Hara's Tower, whence it falls steeply to the plateau of Windmill 

 Hill, some 250 ft. above the sea and thence precipitously to 

 Europa Flats at about 100 ft. The shore, except at the North 

 Front and Catalan Bay, and a few points on the western side, is 

 precipitous or artificial, consequently but few maritime plants are 

 found, these being chiefly at Europa Point and Catalan Bay. The 

 slopes are covered with much shrubby vegetation, often difficult 

 to penetrate, and in recent years a considerable number of pine 

 and other trees have been planted on the w^estern slopes. The 

 Alameda Gardens and the slopes towards Eosia were formerly 

 much wilder, and parts of them were cultivated for vines and 

 cereals. In this neighbourhood doubtless several of the species 

 which are now extinct were to be found. On the east side a 

 steep slope of sand gives a foothold for several species which only 

 occur there and on the Neutral Ground, but doubtless formerly 

 also grew on the North Front. Modern improvements and water 

 catchments are rapidly destroying this interesting habitat. Bras- 

 sica painllaris has already disappeared from its only known 

 station. 



Gibraltar, which has 587 native species, has a markedly diffe- 

 rent flora from that of the neighbouring parts of Spain. This is 

 due to its limestone formation, the absence of water or damp 

 places, the rarity of sand dunes, and the almost total absence of 

 agriculture. Thus Ericacea are totally absent, while many other 

 genera and species, which are quite common in the neighbour- 

 hood, are absent, or at least very rare, on the Eock. There are at 

 least 236 such species, without reckoning moisture-loving ones. 

 Another cause, which, however, has tended to a reduction of the 

 number of species ratlier than to their nature, is to be found in 

 the alteration to tlie western slopes. Formerly these slopes were 

 open to the browsing of goats, so that the shrubs were rarely 

 allowed to rise to a greater height than three or four feet, allowing 

 plenty of room between them for smaller plants, but now the 

 planting of trees and the erection of an unclimable fence at a low 

 elevation, have kept out the goats, so that the taller growths have 

 been encouraged and crowded out much of the undergrowth. 

 Gaudichaud remarks upon the total absence, in 1817, of all trees 

 taller than Chanicerops luDnilia, though this must have Ijocn an 



