Haageocereus lachayensis Rauh & Backeb. 

🌱 Morphology
     A columnar cactus with a rigid and upright habit, featuring green stems that can grow straight or slightly arched and reach 1–2 m in height, forming clumps of several stems from the base as they age. It has 12–14 ribs, somewhat tuberculate towards the apex. The areoles are very close together, yellow to dark brown, and feature fine yellowish wool. It stands out for its dense and persistent spination: it generally develops one very robust central spine, directed downwards, 2–4 cm long, which may reach a greater length in some specimens, accompanied by 20–30 radial spines, occasionally up to 40, arranged in 2–3 series. Young spines are yellow or golden and darken progressively until they acquire brownish-black tones, creating one of the most characteristic features of this form.

🌍 Distribution, habitat, and family
It is native to the Lomas de Lachay, in the Lima region, Peru, where it forms extensive populations in the low and stony areas of the ravines. It inhabits one of the extremely arid coastal ecosystems of Peru, conditioned by the seasonal presence of fog. It is found at approximately 100 to 800 m of altitude in this locality. The name lachayensis refers precisely to the Lomas de Lachay. It belongs to the family Cactaceae, subfamily Cactoideae, tribe Trichocereeae. 

❄️ Temperature · USDA Zone 9b
It tolerates minimum temperatures of down to −4 ºC when dry and with well-acclimated specimens. In cultivation, it is advisable to protect it from prolonged frosts and, especially, to avoid low temperatures coinciding with a damp substrate.

☀️ Lighting
It needs very intense lighting and several hours of direct sun to maintain compact growth and develop its characteristic golden spination. Intense exposure can produce a bronze tone in the epidermis and favors the production of spines and flowers. As a general guideline during active growth, a DLI PAR of 20–30 mol·m⁻²·day⁻¹ is recommended.

💧 Growth cycle and watering
Winter rest. During the cold period, it should be kept practically dry, especially when temperatures are low. In spring and summer, with sufficiently high temperatures, growth resumes and it can be watered abundantly but sparingly, allowing the substrate to dry completely before the next watering. Ventilation and rapid drainage are especially important in this species from desert environments.

🌸 Flowering
It produces large, tubular to slightly funnel-shaped flowers, approximately 6–8 cm long and 5–6 cm in diameter. The floral tube is greenish, widening towards the upper part, and covered in abundant white trichomes; the perianth segments are white or pale pink. The flowers open mainly at night and may remain open until the next day. Recent studies on H. acranthus in the coastal hills show a floral biology compatible with pollination by vertebrates, including bats and birds.

🌿 Nutrition
During the active growth period, a fertilizer with a high content of assimilable calcium and low levels of nitrogen, such as Desert CHOICE® Cactáceas, is recommended, applied once a month when watering. Before flowering, it can be supplemented with Desert CHOICE® Floración.

This is an inimitable xerophyte grown in Madrid in a technological square pot, with the substrate activated by mycorrhizal fungi.