Trichocereus macrogonus

• Body: Stout (although it may be slender in cultivation) bluish green, particularly on young growth, to over 6.5' (2m.) high. Branches 2.75” (7cm.) diameter, more or less frosted at first.
• Ribs: Usually 7, rounded, .6” (1.5cm.) high, separated by depressions over the areoles.
• Areoles/Spines: Gray areoles, .6” (1.5cm.) to .75” (2cm.) apart. Horn colored to brown spines, later blackish or dark gray or grayish-brown. Six to 9 radial spines, tapering to a fine point, from .2” (.5cm) to .75” (2cm.) long. Central spines stouter, to about .75” (2cm.) long.
• Flowers/Fruit: White flowers, to 7” (18cm.) long, broadly spherical.
• Distribution: South America (not reported in the wild).

Trichocereus manguinii

• Body: Dark grayish-green, erect, branching freely from below to 37.5” (95cm.) high with up to 4.3” (11cm.) diameter stems. Often confused with T. schickendantzii.
• Ribs: 18-20
• Areoles/Spines: Areoles slightly sunken. Spines brownish; ~11 radial spines; up to 5 central spines to .15” (4mm.) long.
• Flowers/Fruit: Flowers very broad, white, to 6.25” (16cm.) long.
• Distribution: Northeast Argentina or Paraguay?

Trichocereus neolamprochlorus

• Body: Colony forming, branched from base to about 20” (50cm.) high. Starts glossy, light green, later more dirty green. Stems to 3.1” (8cm.) diameter. Often confused with T. lamprochlorus.
• Ribs: 9-10, rounded with transverse depressions.
• Areoles/Spines: Spines fine, stiff, pale yellow with reddish below; 15-18 with 4 stouter spines to .75” (2cm.) long recognizable as central spines.
• Flowers/Fruit: White flower to 9.5” (24cm.) long, 6.2” (16cm.) diameter. Green oblong-spherical fruit, sparsely hairy.
• Distribution: Northwest Argentina (Jujuy and Mendoza, Cordoba).

Trichocereus nigripilis

• Body: Stems to 2.75” (7cm.) diameter, erect to prostrate and then ascending to 40” (1m.) tall.
• Ribs: To ~12.
• Areoles/Spines: Areole dark gray, .4” (1cm.) large. Spines gray, darker above, reddish when seen against the light. Approximately 12 radial spines to .4” (1.1cm.). Six lateral central spines to .6” (1.5cm.) long.
• Flowers/Fruit: White flower, ~2.5” long.
• Distribution: Coquimbo, Chile.