The Saguaro is an icon of the West in the US. These are commonly shown in cowboy films, making them the most well known succulent in the cactus family. These grow extraordinarily slowly up to 16 meters (50 feet) tall and may persist up to 200 years. While not in immediate danger of extinction, these are heavily protected by law.
Carnegiea gigantea (Saguaro)
Hardiness Zones: 9-11
Height: up to 16 meters (50 feet) tall
Diameter: trunk to 75 centimeters (30 inches) wide
Growth Rate: very slow, sometimes only an inch per year above ground
Age: Branches begin to grow at around 75 years old, may persist to 200 years old.
Root System: extensive lateral roots with a taproot to 1 meter (3 feet) deep, smaller roots may expand radially as far as this cacti is tall
Tolerates: drought, dry soils, extreme heat
Problems (major): Growth is extraordinarily slow. Root rot may occur in overly moist or poorly drained soils.
Problems (minor): none
Poisonous: presumably no
Soil requirements: prefers humusy, extremely well-drained soils, native to sandy soils
Air requirements: low humidity
Watering requirement: low
Sun requirement: full sun
Primary photosynthetic organ: stem
Stem shape: cylindrical, ribbed
Leaf shape: spines grow in vertical rows, to 5 centimeters (2 inches) long
Flower structure: white, sweet-scented, yellow center, to 13 centimeters (5 inches) wide, pollinated by birds, insects, and bats
Flowering frequency: May, open at night, persist for one day
Fruit: ovular, red, edible, spiny, to 10 centimeters (4 inches) in diameter, split open in June or July
Seeds: small, black, 0.3 centimeters (0.1 inches) wide
Reproduction by offsets: yes
Monocot or dicot: dicot
Shape: columnar with upright vertical branches
These may weigh up to 12 tons and survive to 200 years old. Saguaro are the largest succulents in the cacti family (Cactaceae) and are arborescent, with woody ribs.
These are rarely grown as ornamentals.
A mature Saguaro in bloom during May (originally uploaded by Leonard G. on 28 May 2006)
Visible, arborescent ribs on a mature, dead cactus (uploaded by Wikipedia User:Postdlf on 20 December 2004)
Mature flowers (uploaded by Wikipedia user:dcirovic on 25 April 2009, author Dan Hiris)
Saguaro spines (uploaded by Wikipedia user Mwinog2777)
I do not own the rights of these images; all credit goes to its original creator(s).