The encyclopdia britannica; a dictionary of arts, sciences, literature and general information . cylindrical, columnar or flattened into leafyexpansions or thick joint-like divisions, the surface being eitherribbed like a melon, or developed into nipple-Uke protuberances,or variously angular, but in the greater number of the speciesfurnished copiously with tufts of horny spines, some of which areexceedingly keen and powerful. These tufts show the positionof buds, of which, however, comparatively few are stems are in most cases leafless, using the term in a popularsense; the leave
The encyclopdia britannica; a dictionary of arts, sciences, literature and general information . cylindrical, columnar or flattened into leafyexpansions or thick joint-like divisions, the surface being eitherribbed like a melon, or developed into nipple-Uke protuberances,or variously angular, but in the greater number of the speciesfurnished copiously with tufts of horny spines, some of which areexceedingly keen and powerful. These tufts show the positionof buds, of which, however, comparatively few are stems are in most cases leafless, using the term in a popularsense; the leaves, if present at all, being generally reduced tominute scales. In one genus, however, Peireskia, the stems areless succulent, and the leaves, though rather fleshy, are developedin the usual form. The flowers are frequently large and showy,and are generally attractive from their high colouring. In onegroup, represented by Cereus, they consist of a tube, more or lesselongated, on the outer surface of which, towards the base, aredeveloped small and at first inconspicuous scales, which gradually. Fig. I.—Prickly Pear {Opunlia vulgaris). I, Flower reduced; 2, Same in vertical section; 3, Flattenedbranch much reduced; 4, Horizontal plan of arrangement of flower. increase in size upwards, and at length become crowded, numer-ous and petaloid, forming a funnel-shaped blossom, the beautyof which is much enhanced by the multitude of conspicuousstamens which with the pistil occupy the centre. In anothergroup, represented by Opuntia (fig. i), the flowers are rotate,that is to say, the long tube is replaced by a very short one. Atthe base of the tube, in both groups, the ovary becomes developedinto a fleshy (often edible) fruit, that produced by the Opuntiabeing known as the prickly pear or Indian fig. The principal modern genera are grouped by the differencesin the flower-tube just explained. Those with long - tubedflowers comprise the genera Melocactus, Mammillaria, Echino-cactus, Cereus
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectencyclo, bookyear1910
