Stem, areoles and spines
In the 2018 taxonomic description, stems are cylindrical, up to about 100 cm tall and 18 cm in diameter. They may remain solitary or branch laterally near the base to form loose clusters. Wax covers the grey-green surface, and grey wool shelters the apex. The roots are fibrous. [Larridon et al. 2018, description of C. cinerea]
The main species description gives 12–26 ribs and round areoles less than 7 mm in diameter. Spines are usually black at first and become grey with age. Their number and length vary greatly among subspecies. krainziana, with its numerous hair-like spines, is particularly distinct. In columna-alba, the number of ribs can greatly exceed the range typical of the nominate subspecies. [Larridon et al. 2018]
Flowers and subspecies
The flowers are pale yellow, about 2.5–3.5 cm long. Fruits are pink to red, about 1–1.5 cm long, with few scales. Smooth, ovoid seeds reach about 1.5 mm. Features of the ribs, branching and spines help identify the subspecies listed in the table. [Larridon et al. 2018]
| Podgatunek | Stem and ribs | Ciernie lub kwiat |
|---|---|---|
| cinerea | Often branched, up to 26 broader ribs | Outer perianth elements with a reddish tip or stripe |
| columna-alba | Usually solitary, up to 40 ribs, exceptionally 50 | Paler perianth without the red tips typical of the nominate subspecies |
| krainziana | Loose clusters, stems up to about 20 cm in diameter | Up to about 30 thin, flexible spines per areole, up to 3.5 cm long |
Distribution and studies of species boundaries
The range includes coastal parts of the Antofagasta and Atacama regions in Chile. Individual subspecies occupy different parts of this belt. The nominate subspecies is associated with the Taltal area, columna-alba with valleys and plains farther south, and krainziana with a restricted area of hills near Taltal. [2-WWW] [Larridon et al. 2018]
The 2018 analysis compared chloroplast sequences with microsatellite markers. Different types of data showed different degrees of separation among populations. Chloroplast markers supported recognition of C. gigantea, while microsatellites revealed high variation and a less pronounced structure. The authors considered gene flow and the limited resolution of the markers used, among other factors. [Larridon et al. 2018]
Orientation relative to the Sun
Northward inclination of the apices was studied in populations of C. cinerea at Paposo and Taltal. In the 1980 experiment, the mean stem angles relative to the horizontal differed between these sites. The study also included today's C. cinerea subsp. columna-alba (C. columna-alba in the paper) and C. gigantea (C. haseltoniana in the paper). The measurements and radiation balance model are described in the article on stem orientation. [Ehleringer et al. 1980] [2-WWW]
Synonyms and names in the literature
Echinocactus cinereus [2-WWW]