Eulychnia species
Date: 1982 August 30
Location: Observatorio Cerro Tololo, Chile
Most likely E. spinibarbis or E. breviflora this plant was about 3 metres tall. There is a 30cm ruler at the base of the plant for scale.
Below, detail of the strong spines of the Eulychnia. You might be able to make out the first signs of flower buds developing on some of the areoles, just above the spine clusters. There is a 5cm lens cap for scale.