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BOTANICAL OBSERVATIONS ON THE AZORES. 89 
sects, and, as a rule, they have open flowers with readily 
accessible nectar or pollen. 
In a group of islands possessing only seven species of 
wild mammals, none of which is peculiar to the islands 
nor commonly concerned with the dissemination of plants 
elsewhere, and few birds capable of aiding in this work 
except for aquatics or marsh plants, it is scarcely to be 
expected that special dissemination adaptations would be 
found on the part of aboriginal plants, which presumably 
have been associated with these animals for a relatively 
short time, nor of recently introduced plants unless the 
relations have been established and the modifications worked 
out before either plant or animal reached the Azores. 
Hence it comes, for instance, that well developed burrs are 
found only on evidently recent introductions, and in most 
cases are obviously less effective than on the continents 
whence the plants producing them came. By far the 
greater number of species either possess no special modifi- 
cation adapting them to certain dissemination, but depend 
upon gravitation, the wind, or hygroscopic movements of 
their seed vessels, or else their adaptations are out of 
harmony with their surroundings. 
Owing to the limitation of many species to cliffs and 
walls, they must needs be able to endure considerable 
drought, and for a protracted period, without serious in- 
jury, and this is found to be the case. But by far the 
greater number of plants showing adaptations to this end 
are those which had acquired these peculiarities before leay- 
ing their original continental home, so that they present 
few, if any, peculiarities properly claiming attention as a 
part of their relations to their present surroundings. The 
same may be said of the structure of strand plants, none 
of which are peculiar to the Azores, but the details of the 
distribution of which, nevertheless, would make a most 
interesting study.* 
* Cf., for instance, Massart, La biologie de la végétation sur le littoral 
belge. Bull. Soc. roy. de bot. de Belgique, 32: 7. 
