star-fish (Astrophyton), a resemblance to which the name Astrophytum, sometimes applied to this plant, owed its origin.  The form of the stem is well represented in the Figure.  The white dots shown on the bark, and which look like scales, are composed of very fine interwoven hairs, which, under a microscope, are very pretty objects.  This species was introduced from Mexico along with the large plant of E. Visnaga described at the beginning of this chapter, and was first flowered at Kew, in July, 1845.  Stems 1 ft. in length were received, along with shorter ones; but only the small ones were established.  The flowers are daisy-like, 11/2 in. across, and are straw-coloured, the petals being tipped with black.  It thrives under warm greenhouse treatment.  When without its flowers, it looks more like a piece of chiselled stone than a living plant.

[Illustration:  Fig. 40.—­Echinocactus myriostigma.]

E. obvallatus (fortified); Fig. 41.—­The form of stem in this species is shown in the Figure.  It grows very slowly plants 4 in. through taking about ten years to reach that size from seeds.  The spines are stout, all deflexed, and arranged along the edges of the numerous ribs into which the stem is divided.  The flowers are developed from the centre of the plant, and are surrounded by the erect spines, which crown the, as yet, undeveloped tubercles.  Two or three flowers are produced at about the same time, each one being composed of a short, spiny tube, and a whorl of erect petals, which are pointed, purple-coloured, paler at the margin, the stamens being yellow.  Native of Mexico.  It requires a stove temperature, and flowers in summer.

[Illustration:  Fig. 41.—­Echinocactus obvallatus.]

E. Ottonis (Otto’s); Bot.  Mag. 3107.—­A dwarf kind, with a balloon-shaped stem, rarely exceeding 4 in. in height, and divided into a dozen wide ridges with sharp, regular edges, along which are clusters of small, brown spines, set in little tufts of wool, and looking like an array of spiders.  The flowers are borne on the tops of the ridges, and are pale yellow in colour, with a band of red hair-like spines surrounding the calyx just below the petals, which are narrow, spreading, and look not unlike the flowers of the yellow Marguerite; the stigma is bright red.  The symmetrical form of the stem, with its rows of spider-like spines, renders this plant attractive, even when without its bright and pretty flowers.  It thrives only in a warm stove.  Introduced from Brazil in 1831, flowering in the month of July.  As it produces young plants about its base, it may be easily propagated by removing them and planting them in soil; or they may be grafted as advised for other of the small, globose-stemmed kinds.