島嶼植羣之趨木性

Woodiness in island flora

The idea that woodiness in otherwise largely herbaceous genera is a basic feature of the ecosystem of oceanic islands is found to be redundant. Woodiness in such genera is also not confined to islands; a scanning of all cases in Hawaii learned that of all these genera woodiness is also found in continental areas. The wrong impression of its uniqueness has probably originated because, as with many other so-called characteristic island features, no comparative studies were made with situations in continental areas. Ratios of woodiness on islands and continents cq. continental areas must still be computed. It is sometimes advanced that woodiness in oceanic islands is due to the notably moderate climate of such islands permitting continued growth and that there is a natural selecting active for plants that are of longer duration, suiting the year-long growing season of such insular islands, an explanation recently phrased by Carlquist in a study on the endemic species of Echium in Macaronesia. In my experience it is in these two island groups as varied as it can be imagined to be on any place of the same size anywhere in the world. And I object against the use of the term natural selection here as it is in these volcanic areas precisely the lack of competition; the prevelance of bare soil and open niches provides natural opportunity for the origin of different life forms unhampered by competition and genomes may show what they are capable of to produce in the patio ludens of form making. In agreement with this is the occurrence of striking, rare life forms in the volcanic areas of East Africa and the Andes.