Origin and Habitat: Brazil (states of Piaui, Ceara, Rio Grande do Norte, Paraiba, Pernambuco, Alagoas, Sergipe and Bahia)
Description: It is one of the most spectacular columnar tree-like cereus 1 to 10 (or more) m tall. It ramify at the base or develops a distinct trunk with dozens of erected glaucous (bluish-silver) branches. Its elegant habit (shape) makes it look like a miniature blue Saguaro. This is one of the bluest columnar cacti.
Stem: Turquoise/ sky blue or light blue-green. Branches 5,5-11 cm in diameter.
Ribs: 5-19 about, straight, with traverse folds visible only at the stem apexes, 15-35 mm wide and with12-24 mm deep furrows,
Pseudocephalium: As Pilosocereus cacti age, they produce what is called a 'pseudocephalium', but in Pilosocereus pachycladus the fertile portion is often slightly differentiated from normal vegetative parts. The floriferous areole are usually located on one or more ribs near the apical part of the branches and produce thick, soft tufts of orange/white hair (sort-of like that seen in 'old man cacti' Cephalocereus senilis). This area of the cactus is where the flowers pop out.
Areoles: 3-10 mm in diameter, 2-12 mm apart with white to grey felt and long white bristles. The areoles that bear flowers very hairy.
Spines: Translucent with yellow hue turning grey as they get old.
Central spines: 1 to 12, straight, directed upwards 1-30 mm long.
Cultivation and Propagation: It grows well, though slowly, but it possible to increase the speed of growth to some extent by providing adequate amount of water, warmth, and an all-purpose liquid fertilizer diluted half strength during the active growing season, but it’s susceptible to rotting if too wet. It likes a sunny position also blasting sun in summer. If grown indoor provide 4 to 6 hours, or more, direct morning or afternoon sun. It should be watered regularly in Summer and kept drier in Winter. It like pots with generous drain holes, need a very porous, slightly acidic potting medium (add pumice, vulcanite, and perlite). It can be grown outdoors in frost-free climates, needs anyway to kept above 54°F (12°C) and dry in winter. But it can tolerate temperatures down to 41°F (5°C) or even 32°F (0°C) for very short periods if very dry and ventilated.
Maintenance: Repot every two years.
Remarks: Do not use fatty products (like horticultural oil, neem oil, mineral oil, and insecticidal soaps) that can fade and ruin the characteristic blue colouration of the epidermis!
Propagation: Seeds or cuttings.
"Pilosocereus pachycladus" Text available under a CC-BY-SA Creative Commons Attribution License. www.llifle.com 14 Nov. 2005. 08 Mar 2021. </Encyclopedia/CACTI/Family/Cactaceae/16443/Pilosocereus_pachycladus>