Stems 25+ cm diam., widest where proximal branches arise; pith 10+ cm diam. Flowers usually ter-minal, 6.5-8.5 cm diam.; scales on flower tubes broadly triangular to rounded, green with red apices; ovary with locule to 25 mm; filaments white, short; anthers tan. Seeds: testa thin. 2n = 22.

Flowering early May-late Jun. Sonoran desert scrub; 180-1400 m; Ariz., Calif.; Mexico (Sonora).

In its habitat Carnegiea gigantea, the saguaro (also spelled sahuaro), is the most conspicuous and most-studied of all North American cacti. It is the tallest cactus of the flora---indeed, these are the tallest trees of the deserts in the United States.

Plant: Massive columnar trees to 15+ m tall. STEM simple or the trunk bearing 1-6(-20+) upright-curving branches usually 2-2.5 m above ground, commonly in subwhorls, sometimes rebranched, to 75+ cm in diameter (widest at lowest branches), green, glabrous but woolly at apices; ribs 12-24, 3-4 cm high, continuous, increasing in number from the narrow base. AREOLES mostly circular, 6-8 mm in diameter, spaced about 2.5 cm apart on rib to nearly contiguous at stem apices, bearing short tan to gray wool Leaves: LEAVES of long shoots minute or obsolete; SPINES yellow to reddish brown, aging gray to gray-black, terete to angular, mostly bulbous-based, divergent; central-most spines stout, 3-5(-10) per areole, mostly l-3 cm long, but the basal one longest, 3.5-5(-8) cm long; peripheral spines finer, 12-15(-19) per areole, 1-2 cm long Flowers: nocturnal but remaining open into morning, solitary in areoles, arranged in masses usually on south sides and below apices of the branches, perfect, actinomorphic, funnelform, (8-)10-12 cm long, 4-6 cm wide; ovary ovoid, bearing fleshy, elliptic scales, these ca. 2 mm long, apiculate, with axillary tufts of short white wool; floral tube scaly, ca. 6 cm long; outer tepals green; inner tepals waxy-white (drying black), reflexed, broadly obovate, ca. 2.5 cm long, apiculate; stamens numerous, exserted, the filaments and anthers cream-white; style and the ca. 12 stigma lobes cream-white Fruit: FRUITS maturing pale red, glabrous, scaly, spineless, ellipsoid to obovoid, 4-8 cm long, splitting longitudinally into 2-4 irregular radiating portions; pulp bright red, juicy, sweet. SEEDS numerous, deep red-brown appearing black, finely pitted, ca. 2 mm long, 1.8 mm wide Misc: Upper Sonoran Desert zone, especially on hills and buttes; below 1600 m (5200 ft); May-Jun, occasionally in Sep REFERENCES: Pinkava, Donald J. 1995. Cactaceae. J. Ariz. - Nev. Acad. Sci. 29(1): 2, 6.

Benson 1969, Kearney and Peebles 1969

Common Name: saguaro Duration: Perennial Protected Status: Highly safeguarded, Salvage restricted in Arizona. General: Upright, a large simple stem with 1 to several lateral branches reaching 16 m tall with branches 30-65 cm in diameter and 12-25 ribs that are obtuse and 1-3 cm high, which varies with water availability. Spines: Aeroles 2-4 cm apart on older growth, crowded at apex of stem, the spines on top needle shaped, yellowish brown and extending forward, the central spine more stout than the radial ones, these up to 7-8 cm long, dark brown to black. Flowers: Nocturnal and 10-12 cm long by 5-8 cm diameter when expressed, the floral tube is 1-1.5 cm long and green with a throat 2.5-3.5 cm long and perianth segments that are waxy white, with white filaments. Fruits: Green berry tinged with red, fleshy, 6-10 cm long, splitting irregularly. Ecology: Found on rocky or gravelly soils on slopes, rocky ridges, outwash fans, canyons, and benches from 500-3,500 ft (152-1067 m), flowers May (rarely in August with rains). Distribution: se CA, s AZ, nw MEX Notes: You know this plant. If not, you-d better learn it. Ethnobotany: O'odham peoples have gathered the fruits using traditional long sticks. The fruit has uses that range from mush, to wine, to jam, syrup, to using the seeds for oil; the plant can be used for splints, furniture, fences and for fodder. Etymology: Carnegiea is named for Andrew Carnegie (1835 1919), while gigantea refers to the enormous size. Synonyms: Cereus giganteus Editor: SBuckley, 2010