VEGETATIVE PROPAGATION. 11 



tion, so that the soil will not shift from one side toward the other 

 when watered. Cactus plants are of slow growth and may remain in 

 the flat for several months before being potted. The proper time for 

 potting is when the plants have grown so large that they begin to 

 crowd each other or when the roots of adjacent plants begin to 

 intermingle. In preparing pots for individual plants the same method 

 should be followed as for the preparation of the germination pots, 

 except that a coarse soil may be used to advantage. It is not advis- 

 able to begin with pots smaller than 2^ inches, as they dry out too 

 rapidly. 



VEGETATIVE PROPAGATION. 



Almost all cacti may be readily propagated from cuttings. The 

 plants are so soft in tissue and so filled with w^ater that any bruise 

 or mutilation is likely to be the point of attack of a rot fungus, which 

 quickly destroys them; so, in making the cutting, a clean, sharp 

 knife must be used and a smooth surface left on the cut end. The 

 cutting should then be placed in a dry atmosphere for a day or 

 more, until, by drying, a kind of cuticle has formed over the cut sur- 

 face. The cutting may then be rooted in sand on a bench or planted 

 directly in pots. In the warmer, drier regions it may be placed 

 directly in the open ground, provided the soil has perfect drainage. 

 In greenhouse culture it is best not to place much of the cutting 

 below the surface of the soil or sand; 1 inch is sufficient for large 

 plants, and less than that for smaller ones, in proportion to the 

 size of the cutting. When the cutting is long and likely to fall 

 over, a stick should be inserted in the soil by its side and the two 

 securely tied together until roots have been formed. When mature 

 plants are shipped in from the field the roots are always more or 

 less injured. It is always best to cut away the roots, let the wounds 

 dry and heal for a time, and then plant them as cuttings. Many 

 of the opuntias are naturally adapted to propagate themselves 

 vegetatively. The stems are readily detached at the joints. These 

 stems fall to the ground and in a short time develop roots and begin 

 to grow as independent plants. Some are adapted for even wider 

 dissemination. The spines which they bear are very sharp and 

 stiff, and are barbed. These spines penetrate the skins of passing 

 animals and cling so tenaciously that the joints bearing them are 

 readily detached from the parent plant and may be carried a con- 

 siderable distance before being released from their carrier. Once 

 lodged in proper soil under favorable climatic conditions, they soon 

 become new individual plants. In many of the opuntias the fruits 

 are sterile but proliferous. They may be removed and treated as 

 cuttings and will readily produce new plants. Many of the smaller 

 forms, such as Echinocactus, Echinocereus, and Mamillaria, pro- 



262 



