In one group, represented by Cereus, they consist of a tube, more or less elongated, on the outer surface of which, towards the base, are developed small and at first inconspicuous scales, which gradually 0000 FIG.
Those with long - tubed flowers comprise the genera Melocactus, Mammillaria, Echinocactus, Cereus, Pilocereus, Echinopsis, Phyllocactus, Epiphyllum, &c.; while those with short-tubed flowers are Rhipsalis, Opuntia, Peireskia, and one or two of minor importance.
The yellow Micrococcus cereus-flavus and the B.
The plants are nearly allied to Cereus, differing chiefly in the floriferous portion developing these longer and more attenuated hair-like spines, which surround the base of the flowers and form a dense woolly head or cephalium.
In the north-eastern portion the Budorus flows into the Aegean, being formed by two streams which unite their waters in a small plain, and were perhaps the Cereus and Neleus concerning which the story was told that sheep drinking the water of the one became white, of the other black.
The western dry areas have the old-world leguminous Astragalus and Prosopis (Mesquit), but are especially characterized by the northward extension of the new-world tropical Cactaceae, Mgmmillaria, Cereus and Opuntia, by succulent Amar llideae such as A gave (of which the so-called American aloe is a type), and by arborescent Liliaceae (Yucca).
Proceeding southward cacti become common, first a dwarfed species, and then a larger columnar form (Cereus quisco).