BOTANICAL GEOGRAPHY. 449 



garis. b. Thin forests of Pinus sylvestris (5000' 6500'), of small extent on 

 the Sierra Nevada, the trees being only from 20' to 30' in height ; on the 

 Serrania de Honda, the Pinsapo forest previously mentioned with isolated 

 trees of Taxus (5000' 6000'). The Sierra de las Almijarras, south of the city 

 of Granada, is also partly covered with fir trees up to the summit (vid. sup.), 

 hence the present forests appear to be only the remains of the zone of Coni- 

 ferse, which once covered the whole of these mountains, and is now destroyed. 

 In the nuviatile valleys of the Sierra Nevada, isolated groups of trees, forming 

 the remains of large forests, among which are the following, part of which 

 only occur as single trees : Sorbus Aria (5000' 6500'), Cotoneaster grana- 

 tensis (5000' 6000'), Adenocarpm decorticans (4500' 5500'), Acer opulifo- 

 lium (5000' 6000'), Fraxinus excelsior (3000' 5000'), Salix Caprea (600(7 

 6500'), and Lonicera arborea (6000' 7000'), which are the tallest trees grow- 

 ing there. c. Thorny, low shrubs of a stunted-growth form, an isohypsilous 

 formation with a, which is principally found on a calcareous soil : Erinacea 

 hispanica, Genista horrida, Astragalus creticus, Vella spinosa, and Ptilotri- 

 chum spinosum. This region also contains numerous rock plants, particularly 

 those belonging to the limestone ; lastly, boggy springs, with limited mea- 

 dows, exist in the valleys, and these are the localities where most of the 

 Central European species exist. Formations which in my opinion should be 

 enumerated as belonging to the alpine region : a. Formation of the Piorno 

 (Genista aspalathoides} . This shrub, which is sometimes locally replaced by 

 Juniperus nana and Sabina, forms a broad, connected zone of vegetation 

 ( 8000'), and is distributed downwards, like the Rhododendrons, over a tract 

 which extends for a considerable distance into the forests ( 5500'). b. Isolated 

 pastures of rigid Grasses occur on the sloping ground between the Piorno- 

 thickets. They consist of Avena filifolia, Festuca granatensis, and durius- 

 cula, and Agrostis nevadensis, Among the endemic forms of Boissier's third 

 region, in addition to those already mentioned, we have the following, e. g. 

 Sarcocapnos crassifolia, Silene Boryi, tejedensis, and nevadensis, Arenaria 

 pungens and armeriastrum, Erodium trichomanefol'mm, and 3 other species, 

 Anthyllis tejedensis and Ramburei, Astragalus nevadensis, Prunus Ramburei, 

 Saxifraga Haenseleri, Reuteriana, arundana, biternata, and spathulata, Reutera 

 gracilis and procumbens, Butinia bunioides, Scabiosa pulsatilloides, Pyretkrum 

 radicans and arundanum, Senecio Boissieri and elodes, Haenselera granatensis, 

 Odontites granatensis, Thymm granatensis and membranaceus, Teucrium fra- 

 gile, compactum, and other species, and Passerina elliptica and nitida. 



Fourth region (region of snow), 8000' 11,000'. Isolated patches of snow 

 never entirely disappear : a connected layer of snow covers the ground for 

 at least eight months. The soil is constantly kept moist, even in the summer, 

 by the melting snow. Chalets are no longer met with, although cattle are 

 driven up to this elevation. The vegetation consists of alpine herbs and 

 grasses. Only four species of low shrubs belong decidedly to this region, 



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