Xerophyte

Central Spines

Single or rarely 2 or 3, stouter and darker than the radials up to about 4,5 cm long. Older spine on the trunk often very long stout up to 10-11(-16) cm long.

Description

Cereus forbesiiSN|7058]] is a much branched shrubby or treelike cactus, with blue-green cylindrical-columnar stems armed with long spines. It attains a height of about 2 meters (sometimes 7 m or more tall with a distinct trunk up to 40 cm in diameter). In spring to early summer it produces large funnel-form flowers which are white or pinkish white inside and reddish in the exterior.

Flowers

Solitary, lateral, white to reddish,16.5-20 cm long, 8-12 cm in diameter. Pericarpel 25 mm long 18 mm wide. Tube pale green, naked with few small scales. Outer perianth-segments reddish with a green midrib, obtuse, the inner white or pinkish. Filaments white, greenish near the base. Anthers dark-brown or blackish. Pollen grains cream. Style green below, white up to 10 cm long. Stigma-lobes about 16-20 yellowish-white, up to 2 cm long.

Ribs

4 to 7(-8), compressed, obtuse, 20-25 mm hight, attenuating in the older part of the plant.

Stem

Branches cylindrical, succulent, 5 to 10 cm thick (to 13 cm at the base), glaucous blue when young becoming grey-green or light olive-green later.

Radial Spines

about 2-5, short, stout, 1 to 2 cm long, yellowish to pale brown with darker bases becoming grey with age, mostly from the lower part of the areole.

Areoles

Small (4-5 mm Ø), round, with scarce short yellowish-white wool becoming grey or blackish with age.