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lose their leaves in the beginning of the summer, and get the new 

 leaves at the commencement of the rainy season. In the Botanical 

 Gardens in Copenhagen Euphorbia atropurpurea Brouss., E. regis 

 Jubae Webb and the Maroccan E. mauritanica L. are cultivated. 

 All these lose their leaves in the beginning of June, and get new 

 leaves in October. 



In literature little can be found about the frequency of the 

 summer-fall in the adjacent countries, and especially but little is 

 said about the times for spring and fall of the leaf. One so 

 marked summer-fall among the species which grow in multitudes 

 as that of the Canaries seems, however, to take place nowhere in 

 southern Europe. On the other hand is it, according to Volkens 1 ), 

 common in the Egyptian Desert. Also in the deserts and sbrub- 

 steppes of California 2 ) summer-fall is very common. In the low-country 

 region of Madeira summer-fall occurs only in the herbaceous Sonchus 

 ustulatus Lowe, and a few rarer species. Genista virgata Ait. loses in 

 the low-country most of its leaves in the summer, but is evergreen in 

 the high-country. Asparagus umbellatus Link is on Tenerife nearly 

 without any cladodies in the summer; while on Madeira it is green. 

 The Canarian Euphorbias are represented on Madeira by the ever- 

 green E. piscatoria Ait. The other, above mentioned, deciduous 

 species have no vicarious species i Madeira. 



In the damp maquis and forests in the high-country of the 

 Canaries I found summer-fall in the two ferns only: Davallia 

 canariensis Sm. and Polypodium vulgare L., which grow on rocks 

 or on old trunks of trees. 



In the desert region, over the belt of clouds of Pico de Teyde, 

 no instance was found of summer-fall. The coherent maquis con- 

 sisted at its upper limit of the dwarfish Adenocarpus viscosus 

 Webb. Higher up stood, with long intervals, shrubs of Cytisus 

 proliferus L. (densely villose leaves) and Spartocytisus nubigenus 

 Webb (very small leaves). This latter was leafless only upon the 

 branches which wore ripe fruit; the other branches were covered 

 all over with leaves. That summer-fall of the leaves is not found, 

 notwithstanding the desertlike dry summer, is a natural consequence 

 of the long, cool winter. Summer is, however, the better time. 



*) Die Flora der ägyptisch-arabischen Wüste. Berlin 1887. 

 2 ) Parish: A Sketch of the flora of Southern California. Botan. Gazette 

 Vol. XXXVI 1903. 



