Parodia werdermanniana aka Parodia Werdermanniana

Parodia werdermanniana is a small cactus in the Cactaceae family. Kew gives its native range as southern Brazil to Uruguay. LLIFLE describes a small, broken range in Tacuarembó, Uruguay. There, it grows on sandstone cliffs and flat-topped hills. It also clings to steep rock faces at lower sites. Most known groups face south or southeast. Its native climate is subtropical. Older names include Notocactus werdermannianus and Wigginsia werdermanniana.

The plant tends to grow as one stem. Damage to its tip can cause several branches to form. Its yellow-green stem is round or shaped like a club. The top has a slight dip. Stems reach about 0.43 feet (0.13 metres) tall. Their width reaches about 0.33 feet (0.10 metres). Up to 40 low, straight ribs run down the stem. Each rib bears chin-like bumps below the areoles, which hold spines.

Four stout central spines form a cross at each areole. The lowest spine grows longest, and all lean outward. These spines tend to be yellow, but some are red or brown. Each can reach about 0.05 feet (0.015 metres) long. Another 10–20 shorter radial spines surround them. These pale spines may lie close against the stem or stand outward. Spine colour and plant shape vary within the species. Plants once sold as distinct varieties can share traits with intermediate forms.

Glossy yellow flowers open near the stem tip. Six or more can appear together around the crown. Each flower can reach 0.20 feet (0.06 metres) long. Its width can reach 0.23 feet (0.07 metres). The small stem and large blooms give the plant its display value. Fine ridges run lengthwise along the seed surface. The supplied sources give no fruit details or flowering season. They also provide no evidence of food uses or toxicity.

LLIFLE describes this cactus as easy to grow. It needs a mineral-based potting mix that drains well. A neutral to slightly acid mix suits it. Give it warmth and bright light, with some shade. Avoid fierce summer sun. It can take more water while growing, but needs dry winter conditions. Cold, wet soil can cause rot and root loss. LLIFLE recommends a bright greenhouse kept at 8–10°C or warmer through winter. It also reports brief survival at temperatures down to −5°C. Growers can raise new plants from seed or cuttings. Root suckers offer another option when the plant produces them.