Growth form, ribs and spines

In the 2018 revision, clumps reach about 2 m in diameter and 1 m tall. Elongated stems reach up to 25 cm in diameter. Wax covers their pale grey-green surface, and orange-brown wool occurs near the apex. The root system is fibrous. [Larridon et al. 2018, description of C. gigantea]

The number of ribs reaches 40. Ribs are broad, with distinct tubercles and a notch below the areole. Areoles are about 1 cm in diameter and lie up to 2 cm apart. They usually bear 3–7 radial spines and up to one central spine. The rigid, honey-yellow spines reach about 2–4 cm. [Larridon et al. 2018]

Flower, fruit and distribution

Pale-yellow flowers are about 4–4.5 cm long. The outer perianth elements have reddish tips, and reddish scales occur on the flower covering. The fruit is pale red, oval and about 1.5 cm long. Seeds are oval to pear-shaped, about 1.5 mm. [Larridon et al. 2018]

The species occupies rocky coastal areas of the Antofagasta region, from near Izcuña and Caleta Colorado to areas north of Taltal. The 2018 review separates it from C. cinerea, combining morphological, geographical and molecular data. [Larridon et al. 2018] [2-WWW]

Dew and spine microstructure

Malik and colleagues studied C. gigantea under the name C. cinerea var. haseltoniana. In the 2016 observations, dew droplets moved along the spines towards their bases, including along sections pointing uphill. Spine surfaces contained longitudinal microgrooves and structural changes along the conical axis. [Malik et al. 2016] [2-WWW]

Labelling water with fluorescent nanoparticles provided evidence of its movement into stem tissues after wetting only the spines. The proposed mechanism combines spine geometry with a pressure gradient within the droplet and surface wetting properties. A separate article presents the experimental setup, scope of measurements and a diagram of the direction of movement. [Malik et al. 2016]

Stem orientation and older names

The species was also included in the 1980 orientation study as Copiapoa haseltoniana. For 50 plants from Paposo, the mean angle of the stem axis relative to the horizontal was 42.1° ± 8.8° standard deviation. Linking the current name brings both sets of physiological results together. [Ehleringer et al. 1980, Table 1] [2-WWW]

The synonyms also include the combinations C. cinerea subsp. gigantea and C. cinerea subsp. haseltoniana. Original bibliographic titles retain the authors' wording, while study descriptions use the current name with the historical name in parentheses. [2-WWW]

Synonyms and names in the literature

Copiapoa haseltoniana · Copiapoa cinerea var. haseltoniana · Copiapoa cinerea subsp. haseltoniana · Copiapoa cinerea var. gigantea · Copiapoa cinerea subsp. gigantea · Copiapoa eremophila · Copiapoa tenebrosa [2-WWW]