Compact cushion and leaves
Branches grow so densely that leaves on neighbouring stems touch. Specimens examined by Mauseth were about 1 m in diameter and 10–15 cm high. Even older axes remained soft and retained a full circular cross-section. Much of their volume consisted of cortical parenchyma with mucilage cells. [Mauseth 1999, p. 308]
Leaves are narrow and fleshy, with stomata and palisade tissue around their circumference. This species lacks short shoots of the structure described for M. patagonica. Dense branching provides mutual support between neighbouring axes. Flowers and fruit emerge above the green cushion surface, as documented in Leuenberger's series of photographs of wild and cultivated plants. [Mauseth 1999, Leuenberger, ryc. 77–86] [Leuenberger 2008, Leuenberger, ryc. 77–86]
Anatomy at different elevations
Cabral and coauthors compared three populations in the Biobío region. In each, they selected 30 cushions of similar diameter and examined three stems per cushion. Higher-elevation populations had narrower, more densely arranged xylem vessels and lower cushions. The proportion of water in stems was greatest at the intermediate site. [Cabral et al. 2016]
| Cecha | Gomero | Cabrero | Laguna del Laja |
|---|---|---|---|
| Xylem vessel diameter | 4,55 µm | 4,09 µm | 3,96 µm |
| Vessel density | 1209,2 mm⁻² | 1387,5 mm⁻² | 1394,2 mm⁻² |
| Cushion height | 16,3 cm | 14,5 cm | 11,0 cm |
| Water proportion in fresh stem mass | 0,71 | 0,79 | 0,74 |
Soft wood and water balance
The wood contains vessels, parenchyma and tracheids with broad wall thickenings. Fibres are exceptionally scarce. The material examined lacked extensive fibre clusters and the intraxylary bark typical of older M. patagonica. The small proportion of rigid tissues allows stem volume to change with hydration. [Mauseth 1999]
The plants studied cytogenetically were diploid, with 2n = 22. The chromosome complement was symmetric, with predominantly metacentric chromosomes. The positions of ribosomal regions and DNA content allow comparison with diploid and tetraploid plants of M. patagonica. [Las Peñas et al. 2014]
Observations from cultivation and sowing
Leuenberger photographed a seedling overwintering below zero, with a wrinkled stem and leaves that remained firm. The figure caption gives neither the minimum temperature nor exposure duration. The record documents different organ responses to overwintering without defining a frost-resistance limit. [Leuenberger 2008, p. 79, ryc. 86]
The same series showed germination after seeds had remained in a sowing container for a year and a branching two-year-old seedling. Longer observation and seed origin therefore matter when assessing a sowing. Occurrence in lowlands and mountains spans different conditions, so one population-level result cannot be turned into a fixed parameter for all plants of this species. [Leuenberger 2008, figs. 84–86 and p. 81]
Synonyms and names in the literature
Maihuenia philippii · Opuntia maihuen · Opuntia poeppigii · Pereskia philippii · Pereskia poeppigii [2-WWW]