Espostoa , Oreocereus 

(es-poss-toe' ah, or-ee-o-cer' ee-us)

Common name: Old Man Cactus

Family: Cactaceae, Cactus

Growth rate: slow

Light: full sun

Temperature: warm, cool when inactive to 40ºF

Watering: moderate, dry when inactive with misting on warm days

Fertility: low

Humidity: dry

Soil: cactus

Pests and Problems: root and basal rots if overwatered, occasionally scales

Growth habit, uses: upright effect in desert gardens, pots

Other interest: native to the high Andes of southern Ecuador and northern Peru, where the white hairs help protect from the mountain sun and cold

Propagation: seeds


Espostoa

Common name: Peruvian Old Man Cactus

Height x width: 5-10' x 1-2'

Shape: grayish-green columns often in clumps, straight 20-30 ribs, white areoles with white spines protruding through silky white to brownish hairs (wooly spines)

Flowers: cup-shaped, white to purple, 1-3" long, nocturnal, often foul smelling, seldom indoors

Other interest: named for the early 20th century Peruvian botanist Nicholas Esposto

Species: lanata (Old Man of the Andes, Cotton Ball Cactus)  is most common with pure white wool; about 10 species total


Oreocereus

Height x width: varies with species

Shape: columnar, 10-20 warty ribs, gray wooly areoles with protruding spines through silky white hair

Flowers: pink to purple

Other interest: name from the Greek oros meaning mountain, and Cereus or its former genus, refering to its mountain habitat; formerly in the Borzicactus genus

Species:

Of the 6 or so species, the following are most common.

celsianus (cell-see-aa' nuss)--Old Man of the Mountains, 10' x 3', mature plants are branched, red or tan central spines, pink lopsided flowers

trollii (trol' lee-ii)--Old Man of the Andes, 3' x 2', yellow to red central spines variable in length, only very old plants have lopsided violet flowers
 
 


©Authored by Dr. Leonard Perry, Professor, University of Vermont as part of PSS121, Indoor Plants.

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