CACTACEAE 



Characteristics of the Cactus Family 



HABIT. Shrubs or seldom trees, rarely 50-60 feet high and 

 2 feet in diameter; stems commonly columnar, fluted, succulent, 

 and branched; numerous spines springing from cushions of 

 small bristles (areolae). 



LEAVES. Alternate; simple; mostly reduced to spines or scales 

 or absent; photosynthetic processes taking place in the green 

 parts of the fleshy stems. 



FLOWERS. Regular; perfect; usually single; large and 

 showy; calyx of numerous sepals forming a tube, those of inner 

 series petal-like; corolla showy, of numerous petals; stamens 

 many, inserted on calyx tube; ovary inferior, 1 -celled, with sev- 

 eral parietal placentae and numerous horizontal ovules, styles 

 united into one, stigmas as many as placentae. 



FRUIT. 1 -celled, fleshy (rarely dry) berry, often edible. 

 Seed: numerous and small. 



WOOD. An internal, woody frame or skeleton, made up of 

 a cylinder or a meshed network of strands. 



BUDS. Modified into pulvini or cushions which are usually 

 depressions often consisting of a complex series of spines, wool, 

 glands, and growing points. 



SILVICAL CHARACTERS. Very intolerant; although seed 

 generally produced abundantly, natural reproduction by seed 

 is rather scanty because of unfavorable environment; vegetative 

 reproduction common; typical of very dry desert areas where 

 they are often the only woody plants. 



GENERAL. This family contains about 120 genera and 1,200 

 species; there are 2 genera and 5 species reaching tree size in 

 the United States in southern California, Arizona, and New 

 Mexico. Two species, Cereus schottii Engelm. and Cereus thurberi 

 Engelm,, of southern Arizona and Mexico have columnar 

 branches 20 to 25 feet high but cannot be considered trees as 

 they do not have a definite trunk. 



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