''Cephalocereus senilis'', the old man cactus, is a species of

cactus A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Greek ...

native to

Hidalgo Hidalgo may refer to: People * Hidalgo (nobility), members of the Spanish nobility * Hidalgo (surname) Places Mexico * Hidalgo (state), in central Mexico * Hidalgo, Coahuila, a town in the north Mexican state of Coahuila * Hidalgo, Nuevo Le� ...

and

Veracruz Veracruz (), formally Veracruz de Ignacio de la Llave (), officially the Free and Sovereign State of Veracruz de Ignacio de la Llave ( es, Estado Libre y Soberano de Veracruz de Ignacio de la Llave), is one of the 31 states which, along with Me ...

in central Mexico. It is threatened in the wild, but widespread propagation and popularity in cultivation have reduced the demand on wild populations.

Description

''Cephalocereus senilis'' is a tall, columnar species with clusters of stems that may grow to 5–15 m tall; the individual stems are usually unbranched, being unable to withstand the weight of side branches adequately. The most striking feature is the shaggy coat of long, white hairs suggestive of unkempt hair on an old man. The coat is a particularly striking silvery white on the young cactus; as the plant ages the stem begins to lose its covering. The

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s are red, yellow, or white, though the plant may not flower until 10–20 years old.

Morphology and function of the coat

The hairs are modified spines and they make many a plant appear almost snow-white; they serve to protect the plant from frost and sun. However, the hairs are only the radial spines of the cactus; they conceal formidable sharp yellow central spines that belie the inoffensive appearance of the hairy covering.

Cultivation

''Cephalocereus senilis'' is a very popular cactus in cultivation, grown for its woolly appearance. It prefers a very well-drained

soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...

mix (more so than many other cacti), and much bright sunlight, which encourages growth of the hair.

References

External links

Mauseth Research on CactiUnited States Botanic Garden: ''Cephalocereus senilis''
*
photos on www.cactiguide.com
{{Taxonbar, from=Q312190 senilis Cacti of Mexico Endemic flora of Mexico Flora of Hidalgo (state) Flora of Veracruz Garden plants of North America