DECOEATIVE VALUE OF CACTI. 19 



until in a few days all will have passed the blooming period, which, 

 after an interval of time, will recur. In our northern conservato- 

 ries there are usually three or four such periods during the summer 

 season, averaging about four or five weeks apart. On these occa- 

 sions the display of large white flowers hi abundance in the moon- 

 light is a wonderful sight. Most of the species of Echinocereus pro- 

 duce comparatively large showy flowers in a crown about the ends 

 of the branches. They are very attractive in their highly colored 

 (yellow, orange, red, and purple) waxy flowers, but they do not 

 respond so readily to cultivation as many others, especially in 

 greenhouses. Some species of Echinopsis also produce flowers in 

 abundance for a period of a few days. These are trumpet shaped, 

 upright, about 8 inches long, forming a crown about the top of the 

 plant. They range in color from pure white to pale yellow or rosy 

 pink. 



The chief attractiveness and beauty in cacti as a group 1 is the 

 remarkable symmetry of growth hi the individual plants. The colum- 

 nar, and most of the genera of smaller cylindrical or globular forms, 

 have clean-cut, longitudinal, parallel angles, ribs, or wings, and located 

 on them at regular intervals are the buds, or pulvini, which bear 

 the spines and flowers, and from which side branches may be devel- 

 oped. The coloring of the epidermis of the plant is frequently 

 very attractive. While in most species tins color is some shade 

 of green, many specimens are coated over to a greater or lesser 

 extent with white or bluish glaucousness. In some species the 

 surface is dotted over with very small bunches of velvety white 

 hair, as hi Ecliinocactus myriostigma, E. ornatus, and E. capricornus. 

 Other species are mottled with purple, which in the young growths 

 of E. ingens is arranged in transverse bands, alternating with bright 

 green. The coloring of the spines, too, is often exceedingly attrac- 

 tive, especially in the younger growths. It ranges from pure white 

 to amber, yellow, red, and black. Frequently some of these colors 

 are combined on one spine in either longitudinal stripes or transverse 

 bands, and the perfectly uniform variegation is very striking. The 

 form, structure, and arrangement of the spines are in most instances 

 remarkable and show a wonderful adherence to a definite plan of 

 symmetrical arrangement. In certain species some of the spines 

 have a structure of soft and hard transverse layers from base to tip, 

 giving an uneven though uniformly wavy surface much like that of 

 a goat's horn. The larger number of spines are straight or only 

 slightly curved; others have the end curved in the form of a fislihook. 

 Nearly all of them are rather stiff, but some are soft and featherlike 



1 See Safford, W. E., "Cactacese of Northeastern and Central Mexico, Together with a Synopsis of the 

 Principal Mexican Genera," in Annual Report, Smithsonian Institution, 1908, pp. 525-563, in which are 

 illustrations of many species of Cactaceae. 

 262 



