Name and identification
Astrophytum coahuilense (H.Moeller) K.Kayser is accepted in POWO. Name authorship was checked in IPNI. Older literature placed it within A. myriostigma. External resemblance is strong, especially in young plants. Identification uses a combination of flower, fruit, seed, hair and seedling features. [2-WWW] [3-WWW] [Montanucci 2008] [Montanucci 2024]
Stem, roots and development
The plant forms an initially globose body that becomes columnar, usually densely covered with pale hairs. In the 2024 study, adult plants reached about 65 cm tall and 20–25 cm in diameter, with mention of exceptionally taller specimens. Of 226 plants, 222 had five ribs and four had six. Five ribs are therefore very common but not universal. [Montanucci 2024]
Adults remain spineless. Seedlings may produce pale yellowish spines 1–3 mm long. Juvenile spine colour and structure are among features compared with A. myriostigma and A. capricorne. Body, root and development rate need assessment together. White covering alone does not establish identification. [Montanucci 2008] [Montanucci 2024]
Flowers, fruits and seeds
Flowers are yellow, most often with an orange or red centre. In the series described in 2024, 23 of 26 assessed plants had a coloured throat. Entirely yellow flowers also occurred. Maximum flower width in the description reached 90 mm. Colour exceptions complicate identification from a flower photograph alone. [Montanucci 2024]
Fruits are reddish to purple, partly fleshy and usually open at the base. This distinguishes them from typical A. myriostigma fruits, which split at the apex. Studies also compare seed structure and hairs in the lower flower. Several independent features give more reliable identification than rib shape alone. [Montanucci 2008] [Montanucci 2024]
Range and ecology
POWO lists Coahuila. Field papers also describe neighbouring Durango areas, including Lerdo and Sierra El Sarnoso. The atlas presents the range as southern Coahuila and adjoining Durango sites, noting that this detail comes from field literature. [2-WWW] [Montanucci 2008] [Montanucci 2024]
The species grows among rocks at dry sites. Of 114 plants studied, 79.8% occupied open sites and 20.2% partly sheltered sites. Annual rainfall of 177–245 mm was reported for four sites in the climate analysis. These data concern specific locations and the author's climate sources. [Montanucci 2024]
Distinctiveness and the origin hypothesis
The 2008 study assembled arguments for species distinctiveness. The 2024 paper compared plant features and crossing results. Attempts to cross A. coahuilense with A. myriostigma often failed to produce mature, viable offspring. Some seeds nevertheless germinated. The reproductive barrier should therefore be described as strong limitation, rather than complete impossibility of every pollination. [Montanucci 2008] [Montanucci 2024]
The morphological hypothesis of an ancient hybrid origin proposes contributions from lineages associated with A. capricorne and A. myriostigma. The 2024 study supports this interpretation but provides no conclusive nuclear genome analysis. If confirmed, historical hybridisation describes an evolutionary process. It does not automatically change current species status in the atlas. [Vázquez-Lobo et al. 2015] [Montanucci 2024]
Cultivation in Poland
After acclimation, plants can benefit from strong light and airflow. Dry habitats support careful root management and protection from persistent pot moisture. The mixture should retain porosity, and watering should occur during active growth. Assess roots before abruptly increasing watering after prolonged drought. [Szychowski b.d.c] [Anonim b.d.e] [Montanucci 2024]
The archived profile recommends dry overwintering at about 8–10°C. This is cultivation advice, not a measured species threshold. Protect roots during repotting and allow any injuries to heal. Seed propagation and grafting are described in the archived genus account. Use plants of documented provenance when pollinating to preserve the species. [Szychowski b.d.c] [Anonim b.d.e]