12 ORNAMENTAL CACTI. 



duce branches (PL I) which are readily detachable and are easily 

 rooted as cuttings. Some species of Mamillaria have side shoots 

 winch are so lightly attached that they break off by a slight touch. 

 Such plants depend almost entirely on vegetative propagation and 

 rarely produce flowers and fruit. 



GRAFTING. 



Grafting is easily accomplished throughout this whole group of 

 plants. The possibilities of uniting both species and genera seem 

 to be unlimited. For a long time it has been a practice to graft 

 Epiphyllum on Peireskia or some upright, stiff-stemmed Cereus in 

 order to produce a more decorative bush plant. The rat-tail cactus 

 {Cereus flagelliformis) is frequently treated in the same manner. 

 Aside from its ornamental possibilities, grafting may be resorted to 

 profitably as a means of propagation. It not infrequently happens 

 that a plant becomes decayed at its base, and when all evidence 

 of decay or disease has been removed there will be so. little healthy 

 tissue left that it is next to impossible to get it to grow as a cutting. 

 Such a piece may be grafted on a healthy stock and the plant be 

 preserved, if the growing tip is intact. A cleft graft or a saddle 

 graft is more desirable where either of these can be employed, since 

 they require less work in preparation and give a good large surface 

 for the union of the tissues. The mucilaginous sap that exudes 

 from the cut surface of a cactus plant allows the stock and scion 

 to slip apart very easily, and the parts become disarranged unless 

 proper precaution is used to prevent it. For this purpose the needle- 

 like spines of Peireskia or Opuntia may be used. The two parts are 

 pressed firmly together into the desired position, and then a spine 

 is thrust through the united portions, securely pinning them in that 

 position. No wax is required, but it is best to closely wrap the 

 graft with raffia to exclude the air. The grafted plants are then 

 placed in a warm, moderately moist place until the tissues have 

 become thoroughly knitted together. They should not be placed 

 where they might be subject to drying, for under such conditions 

 the cut surface will be the first to dry, and consequently a perfect 

 union will be prevented. 



With small globose or thick plants, such as Mamillaria (PL II), 

 Echinocactus, Echinocereus, etc., a different method is preferable. 

 The head of the plant is cut away with a perfectly smooth trans- 

 verse cut. (PL III.) A stock is selected which has about the 

 same diameter as the scion, and it is also given a smooth transverse 

 cut. The two flat surfaces are then pressed firmly together and 

 held in place by tying them together with a cotton or other soft 

 cord. It is quite essential that clean instruments be used to prevent 



