CIRCULAR No. 66 



JUNE, 1929 



UNITED STATES DEPARTMENT OF AGRICULTURE 

 WASHINGTON, D. C. 



CACTI 1 



By David Griffiths, Senior Horticulturist, Office of Horticultural Crops and 

 Diseases, Bureau of Plant Industry, and Charles Henry Thompson, formerly 

 Assistant Botanist, Missouri Botanical Garden 



CONTENTS 



Introduction 



Propagation 



From seeds 



Vegetative propagation. 



Grafting 



Culture 



Diseases 



Insect pests 



Economic value 



Medicines 



Garden vegetable 



Cactus candy 



Fruits 



Page 

 1 



3 



9 



10 



10 

 10 



11 



11 

 11 



Page 

 Economic value — Continued. 



Wood 13 



Hedges 13 



Decorative value 14 



Single-plant displays 16 



Groupings 16 



Plantings in open ground 17 



Peculiarities of cacti 18 



Attractive investigations with cactus 



subjects 19 



Cultivated forms 21 



Literature cited 24 



INTRODUCTION 



Popular interest in cacti appears to be periodical. Prior to and 

 during 1912 there was a demand for information on this group of 

 plants, but since 1915 there has been a quiescent period until during 

 the last year or two, when there has been a revival of interest which 

 bids fair to become increasingly important. Already cactus collec- 

 tions are being assembled rather numerously, and high prices are 

 being paid for choice specimens. The horticultural trade journals 

 are beginning to reflect the interest, and advertisements of new com- 

 panies and new collectors are appearing. How far the movement 

 will proceed can not be foretold. 



There is a large cactus flora in the United States, and these mate- 

 rials are the ones now most prominently employed. The restrictions 

 on the importation of plant material from Mexico, the cactus region 

 par excellence, may have a decided influence on the development of 

 the business. The interest in cacti is by no means confined to the 

 United States. Already European nurserymen are inquiring about 

 sources of supplies of seeds, cuttings, and plants in quantities. On 

 account of the 10 or more years of comparative neglect, there are no 

 commercial collections of importance. The collectors get what is 

 available in their immediate sections and have little else to offer. 

 The fanciers' collections must consequently be laboriously assembled 

 from widely varied sources. 



1 This circular is a revision and enlargement of Bureau of Plant Industry Bulletin 262, 

 " Ornamental Cacti : Their Culture and Decorative Value," which was published in 1912 

 but has not been available for more than 10 years. 



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