Maihueniopsis hickenii

Segments, spines, flowers and fruit

The description used by Masini and coauthors presents cushions exceeding a metre in diameter and segments up to about 3 cm in diameter. Areoles have hairs and small glochids. Strong spines may reach about 12 cm long. They have a distinct central portion and flattened sides. Small leaves are shed quickly. [Masini et al. 2014, p. 190–191]

Flowers are bell-shaped, with a short yellow perianth. Fleshy fruits resemble stem segments and become yellow-orange when fully ripe. The seed covering is distinctly different from the black seed coat of many globose cacti. It is surrounded by tissue of funicular origin, described in the paper as a compact and relatively soft aril. [Masini et al. 2014]

Range and name in the study

The material studied came from the Auca Mahuida reserve in Argentina's Payunia. The 2014 description reports the taxon in several Argentine provinces, from Buenos Aires and Mendoza to Santa Cruz. The current profile uses the name Maihueniopsis hickenii (in the publication, M. darwinii var. hickenii). POWO accepts M. darwinii separately. [Masini et al. 2014] [2-WWW]

Seed size and germination course

The 21 fruits examined contained 52–111 seeds. Mean seed length was 5.20 ± 0.40 mm, width 4.41 ± 0.35 mm and thickness 2.10 ± 0.19 mm. A total of 100 seeds were measured. The reported standard deviations describe variation in this sample. [Masini et al. 2014, tabela I]

Under a 20/10°C cycle with 12 hours of light and 12 hours of darkness, mean germination across treatments ranged from about 17–26%. Each treatment had 10 replicates of 30 seeds. Before the experiment, seeds were stored for 60 days at 5°C. The comparison included a control, 40 days of cold stratification and two forms of scarification. [Masini et al. 2014]

No treatment significantly increased final germination relative to the control. Stratification accelerated its onset, but the final percentage was lower than in the scalpel treatment. In the latter, part of the outer covering was removed while the seed coat itself was retained. The authors considered physiological dormancy and the effect of the temperature used. [Masini et al. 2014, p. 193–196]