Mammillaria geminispina (Syn. elegans) – Twin-Spined Cactus

Mammillaria geminispina is a clustering cactus species native to central Mexico, particularly in Hidalgo, Querétaro, and San Luis Potosí. It inhabits rocky slopes and dry scrublands, where it anchors itself among limestone outcrops at elevations between 1,500–2,000 m. Over time it develops dense colonies that stabilise the shallow soils of its habitat.

The plant produces globose to cylindrical stems, usually 6–15 cm tall, covered in conical tubercles arranged in spirals. Each areole carries a dense set of white radial spines with two or more longer, darker central spines that point outward, giving the plant a somewhat bristly appearance. As it ages, the species readily offsets, forming compact clumps.

Flowering generally occurs in spring to early summer, with small funnel-shaped blooms arranged in a ring near the crown. The flowers are typically pink to reddish-purple, though shades can vary. These are followed by slender, reddish fruits that contain numerous black seeds, which are dispersed naturally by birds and insects in its native range.

Care Tips:

• Light: Prefers bright light with several hours of direct sun daily; protect from scorching in peak summer heat.
• Water: Water moderately during the growing season, ensuring the soil dries fully between applications. Keep nearly dry in winter.
• Media: Requires a sharply draining mix with a high proportion of grit, pumice, or coarse sand.
• Fertiliser: Apply a diluted, low-nitrogen cactus fertiliser monthly in spring and summer.
• Temperature: Ideal range is 18–30 °C. Can tolerate down to about 5 °C if kept completely dry.
• Repotting: Repot every few years as clusters enlarge, taking care not to damage the roots or spines during handling.