CACTI 



CASSAVA 



227 



prickly-pear burner, as it is called, the spines have 

 been singed from a number of species of cactus 

 common to the Southwest. The Arizona Experiment 

 Station tested several species in this way. (Fig. 

 322.) Previous to the experiment, it had been 



Fig. 322. Singeing the cholla {Opuntia fulgida) with a 

 pricUy pear burner. 



noticed that the stock was browsing on the cactus 

 shrubs, especially on the less spiny fruits. The first 

 fifty plants that were singed were literally devoured 

 by the stock, the prickly peara being eaten nearly 

 to the ground, while only the trunks and woody 

 branches of the chollas remained. It was soon 

 evident that the animals were feeding entirely on 

 the singed cacti, which they readily distinguished 

 from the unsinged. The amount that should be fed 

 from a plant at one time varies with species and 

 condition of growth. 



The machine used costs eighteen dollars. It con- 

 sumes eight to ten gallons of gasoline per day. 

 One man with a machine can feed 400 head of 

 cattle all the spiny cacti they will eat. It is esti- 

 mated that 7,000 to 11,000 pounds of cactus for- 

 age can be prepared daily in this way, at a cost of 

 about two dollars and forty cents, not including 

 the hire of the man. The work and the cost are 

 justified if cattle can thereby be carried over 

 periods of shortage. The amount of water in this 

 forage, as estimated at the Arizona Experiment 

 Station, is approximately 75 to 80 per cent, leav- 

 ing 20 to 25 per cent, or 1,600 to 2,500 pounds of 

 solid matter for the day's work. This large amount 

 of water is of considerable value to the thirsty cattle 

 as it no doubt enables them to browse much farther 

 from their watering places than they otherwise 

 could. 



At the New Mexico Experiment Station, experi- 

 ments were made to test the value of one kind of 

 cactus forage for dairy cows. The spines were 

 singed off in the way mentoned above. The cactus 

 was then run through a root-cutter. When the 

 cows became accustomed to it they ate forty to 

 fifty pounds per day, in connection with a grain 

 ration and a little hay. It seemed to be about 

 equal in value to sugar-beets, pound for pound. 



Composition of cactus forage. 



Analysis of cactus stems and fruit were made at 

 the Arizona Experiment Station, and are reported 

 in Bulletin No. 51 of that station. The ash content 

 of the kinds analyzed was found to be high ; the 

 fiber is low ; nitrogen-free extract is present in 

 high average amount ; protein is more than half 

 that contained in alfalfa hay and about the same 

 as that in grama grass; ether extract is high in 

 the seeds, but the seeds are not digested by the 

 animal ; the fiber content of the seeds is also 

 high. 



Literature. 



For fuller information, the reader should consult 

 Bull. 74 of the Bureau of Plant Industry, United 

 States Department of Agriculture, and Bull. 91 of 

 the Bureau of Animal Industry ; also publications 

 of the Arizona and New Mexico Experiment Sta- 

 tions. Bull. 60, New Mexico, gives results of many 

 analyses of leading species. 



CASSAVA. Manihot utilissima, Pohl. (Jatropha 

 Manihot, Linn. Janipha Manihot, H. B. K.). 

 Euphorbiaeem. Cassava (U. S.), manioc, mandioca, 

 aypi, yuca, and others (S. Amer.), tunglu-bok, 

 simul-alu, tan-u, and others (India). Figs. 323, 

 324. 



By S. M. Tracy. 



A shrubby plant, perennial in the tropics but 

 annual in temperate regions, cultivated for its 

 fieshy roots which are used for the manufacture 

 of starch, Brazilian arrow-root and tapioca, for 

 feeding domestic animals, and for the table. The 

 cultivated forms are not known in a wild condi- 

 tion, but are undoubtedly natives of the American 

 tropics. 



The cultivated form is a shrub three to ten feet 

 in height, the stem and branches forking regu- 

 larly in threes, with long-petioled, palmately- 

 parted leaves having usually five to nine divisions 

 reaching nearly to the base, the sections being 

 entire and elliptical or spatulate in outline. The 

 growing plant bears a strong resemblance to 

 the castor-bean (ricinus), to which it is closely 

 related. The valuable part of the plant is its 

 cluster of fleshy roots, which have a resemblance 

 to the sweet-potato, though often reaching six 

 or eight feet in length. 



While two species have been described as the 

 original types of the cultivated form of cassava — 

 the "bitter," Manihot utilissima, Pohl., containing 

 a considerable quantity of hydrocyanic acid, and 

 the "sweet," Manihot Aipi, Pohl, containing little 

 of the poisonous acid, — recent investigations indi- 

 cate that all the cultivated forms have been 

 developed from a single stock, probably the M. 

 Aipi. Careful structural and chemical examina- 

 tions of a very large number of cultivated forms 

 from Ecuador, Colombia and the West Indies, includ- 

 ing both sweet and bitter sorts, show no constant 

 differences. In different varieties the color of the 

 root may vary from dark red to light yellow or 

 almost white, while the stems and petioles show 



