Myrtillocactus schenckii

Plant structure

Mature plants have been described as trees 3–5 m tall, with a relatively stout trunk and numerous short ascending branches. Their dark green stem surface helps distinguish them from the strongly bluish young stems of M. geometrizans. Closely spaced areoles bear straight radial spines and a distinct central spine. Small, elongate fruits contain black seeds with a sculptured surface. [Britton and Rose 1920]

Distribution and conservation

POWO gives a native range in the Mexican states of Puebla and Oaxaca and in Guatemala. The species is associated with seasonally dry tropical vegetation. The IUCN assessment displayed in the database assigns LC, Least Concern. [2-WWW]

Flowering and pollination

Near San Luis Atolotitlán in Puebla, researchers compared a wild population, plants retained in agricultural areas and home-garden cultivation. Flowering extended from September to March, with peaks differing among management types. Individual flowers in spring remained open for about 11 hours on average. Some flowers observed in winter stayed open into the following day, for about 29 hours. This rhythm applies to the site and seasons studied. [Ortíz et al. 2010]

Flower visitors included the bees Xylocopa mexicanorum, Plebeia mexicana and Apis mellifera. Large Xylocopa bees frequently contacted both anthers and stigma, allowing pollen transfer. Controlled pollination indicated predominantly outcrossed reproduction, using pollen from another individual. Some flowers also set fruit through spontaneous self-pollination, particularly in the home-garden population. [Ortíz et al. 2010]

Selection of plants by people

Ethnobotanical research in the Tehuacán Valley documents retention of plants with desirable fruits during field preparation and transfer of stem pieces into gardens. In the populations compared, cultivation was associated with greater fruit mass and more fruits per branch. Sugar content did not differ significantly among management types. This pattern is consistent with an early stage of domestication in which selection and growing conditions act together. [Blancas et al. 2009]

Germination under controlled conditions

In an experiment comparing four cactus species, M. schenckii germinated most slowly. The water-potential test ran for 40 days at 25°C with 12 hours of light daily. Seeds germinated better at the moderately reduced water potential than at the other two tested levels. This parameter was controlled with a polymer solution in the laboratory. The results describe seed responses within a defined procedure and do not establish a watering schedule for potted seedlings. [Guillén et al. 2009]

Studies of fruit composition

A study of fruit batches identified by the authors as M. schenckii found betalains, ascorbic acid and phenolic compounds. Compared with the analysed batches of M. geometrizans, these fruits contained more ascorbic acid and fewer condensed tannins. The material came from particular harvests, and the authors based identification on unpublished AFLP marker data. The comparison therefore characterizes the batches studied within that identification scope. [Guzmán-Maldonado et al. 2010]

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