Astrophytum capricorne

An Astrophytum capricorne flower with yellow perianth segments and a red centre.
An Astrophytum capricorne flower with yellow perianth segments and a red centre. Photo Konrad Szychowski.

Name and identification

Astrophytum capricorne (A.Dietr.) Britton & Rose is accepted in POWO. The basionym Echinocactus capricornis dates from 1851 and the accepted combination from 1922. Its characteristic spines are long, often flattened, flexible and twisted. Their appearance resembles the goat horns to which the species epithet refers. [2-WWW] [Szychowski b.d.b]

Stem, spines and variation

The initially globose stem elongates with age. In the morphological material described in 2024, plants reached at least 52 cm tall. Eight ribs were most common, with a range of seven to eleven. One areole usually bore five to eight spines, sometimes more. These data concern the material studied and exceed the sizes of young collection plants. [Montanucci 2024]

White hair density and spine colour and thickness are highly variable. The names senile, aureum, niveum, minus and crassispinum occur in archives and collections. POWO places the corresponding older botanical names among synonyms of A. capricorne. Their collectors' meanings remain useful when labels include feature descriptions and provenance. [2-WWW] [Szychowski b.d.b] [12-WWW]

Flowers, fruits and seeds

Flowers open during the day. They are usually yellow with a red or orange centre, of variable intensity. The archived profile gives about 6–7 cm in length. The 2024 paper also documents much larger flowers in the collection studied. The size of an exceptional specimen should not represent a standard species feature. [Anonim b.d.e] [Montanucci 2024]

Fruits are reddish to purple, partly fleshy and usually open near the base. Seed structure favours floating on water. In the 2012 experiment, some seeds stayed at the surface for 30 days. Germination remained relatively high in the hydration treatments studied. The result concerns seeds and a precisely defined experiment. [Sánchez-Salas et al. 2012] [Montanucci 2024]

Range and habitat

The species occurs in northeastern Mexico, including Coahuila. Detailed studies indicate variation among populations and sites, including rainfall and the proportion of sheltered locations. In the 2016 dataset, A. capricorne occupied a drier end of the rainfall gradient than A. asterias and A. ornatum. Mean elevation of 61 records was 1164.1 m above sea level, with a standard error of 36.8 m. [2-WWW] [Carrillo-Angeles et al. 2016] [Montanucci 2024]

Curved spines and white hairs affect the appearance of the plant surface. Without population-specific measurements, assigning a particular physiological advantage to a spine type is difficult. Field material shows both exposed and partly shaded plants. [Montanucci 2024]

Cultivation in Poland

Plants need a bright site, airflow and a mixture permeable throughout the pot. Link watering to growth and root drying. In summer, shelter from days of rain makes outdoor care easier. During heat, observe growth and substrate temperature. Slower growth justifies reducing water, but mild summer conditions do not invariably require drought. [Szychowski b.d.c]

Archived materials give conflicting overwintering temperatures, from 6–10°C in the genus account to about 10–12°C in profiles of some former varieties. No comparative experiment justifies fixed minima assigned to individual names. For a collection without a proven cool overwintering space, a higher, above-freezing range and dry substrate for dormant plants are more cautious. [Szychowski b.d.c] [Anonim b.d.e]

Seed propagation preserves batch variation. Record both parents during pollination. Wery, cited in the author's materials, used Echinopsis for grafting. This is a grower's documented practice. Repotting requires protection of roots from injury and long spines from catching each other. [Szychowski b.d.a] [Szychowski b.d.c]

Forms and identification

The strongly spined form called crassispinum should be distinguished from the horticultural name Crassispinoides. Senile refers to strong spination, aureum to golden spines and niveum to very dense hair covering. These names do not create additional accepted species in this atlas. [2-WWW] [Szychowski b.d.b]