E. texensis (Texan); Fig. 46.—­A short-stemmed plant, with a thick, leathery skin and broad-based ridges of irregular form, crowned with tufts of stout horny spines, the central one much the longest, flattened at the base, and strong as steel.  The flowers are produced near the centre of the top, from the tufts of whitish wool which accompany the spines on the young parts of the ridges.  They are 21/2 in. long and wide; the tube short and woolly; the petals spreading, beautifully fringed, and rose-coloured.  Native of North-east Mexico, where it grows on stony hillsides in full exposure to sunshine, and where, during winter, it has to endure weather verging on to frost.  It thrives in a greenhouse under cultivation.  Like several of the stout-spined, robust-stemmed kinds, this may find favour as a garden plant because of the character of its stem, and the extraordinary strength of its large iron-like spines.

[Illustration:  Fig. 46.—­Echinocactus texensis.]

E. turbiniformis (top-shaped).—­A very distinct dwarf kind, with globular stems 2 in. high and about 3 in. wide, clothed with spirally-arranged rows or ridges of tubercles, similar to those shown in the figure of E. hexaedrophorus, except that, in the former, there are no spines on the mature tubercles, although, when young, they have each a little cluster of fine spines.  The flowers expand in June, several together, from the top of the stem; they are round, 1 in. across, the petals being numerous, pale yellow in colour, tinged with red on the outside.  Introduced from Mexico, 1840.  This curious little plant requires stove treatment, and thrives when grafted on the stem of some other kind.  It is sometimes known as Mamillaria turbinata.

E. uncinatus (hooked); Fig. 47.—­A small species, with oval stems when young, older plants becoming cylindrical, as shown in the accompanying Figure.  The height of the largest plant does not exceed 6 in., so that, when wild, it is often hidden by the long grass in which it is frequently found on stony hillsides at high elevations, in Mexico.  The ridges are broken up into large tubercles, upon each of which is a tuft of short straight spines, arranged in a circle, and a long hooked one springing from the centre, and often attaining a length of about 4 in.  In old plants the spines are almost white, whilst in young ones they are purplish.  The flowers are borne in a cluster on the apex of the stem, and are nearly 2 in. long, the tube being short and spiny, and the petals numerous, arranged in a cup, their colour dark purplish-red, the tips pointed; the stamens are yellow, with orange tips.  The flowers expand only when the sun shines on them, closing up again in dull light, but opening again, and remaining fresh for about a week.  Introduced in 1850.  Flowers in March and April.  This plant may be grown in a cool, sunny greenhouse, or window, requiring only protection from frost in winter, and in summer plenty of light, with a moderate amount of water.  There are several varieties of it described, their differences being chiefly in the shape of the stem.