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

cactus A cactus (: cacti, cactuses, or less commonly, cactus) is a member of the plant family Cactaceae (), a family of the order Caryophyllales comprising about 127 genera with some 1,750 known species. The word ''cactus'' derives, through Latin, ...

native to

Hidalgo Hidalgo may refer to: People * Hidalgo (nobility), members of the Spanish nobility * Hidalgo (surname) Places Mexico :''Most, if not all, named for Miguel Hidalgo y Costilla (1753–1811)'' * Hidalgo (state), in central Mexico * Hidalgo, Coah ...

and

Veracruz Veracruz, formally Veracruz de Ignacio de la Llave, officially the Free and Sovereign State of Veracruz de Ignacio de la Llave, is one of the 31 states which, along with Mexico City, comprise the 32 Political divisions of Mexico, Federal Entit ...

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 Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

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

spine Spine or spinal may refer to: Science Biology * Spinal column, also known as the backbone * Dendritic spine, a small membranous protrusion from a neuron's dendrite * Thorns, spines, and prickles, needle-like structures in plants * Spine (zoology), ...

s 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, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...

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