''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 Gree ...

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 L ...

and Veracruz 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 flowers 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 * Vertebral 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 (zoolo ...

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 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