Mammillaria pectinifera

Name and earlier treatments

POWO accepts Mammillaria pectinifera F.A.C.Weber, published in 1898. The former names Pelecyphora pectinata, Solisia pectinata and Neomammillaria pectinata are in its synonymy. The name Solisia appears in older anatomical studies of this plant's development. The current account connects these names to one species. [2-WWW]

Range and habitat

The current POWO record gives a native range in the Mexican states of Puebla and Oaxaca. The serotiny study by Peters and colleagues concerned a site near Texcala in the Tehuacán valley. Its description places the species on deep, alkaline soils with a relatively high water-holding capacity and numerous stones on the surface. Regional rainfall is concentrated in the summer rainy season. [2-WWW] [Peters et al. 2009, Peters et al., p. 538]

During field observations, rainfall was 267 mm from June 1997 to May 1998 and 817 mm in the following year, compared with the long-term mean of 424 mm given in the paper. This variation provides the background for differences in fruit release and seedling establishment. These values describe specific study seasons rather than a fixed characterisation of every site of the species. [Peters et al. 2009, pp. 538–539]

Stem, flowers and fruits

In the description of the material studied, the stem is globose, about 3–4 cm in diameter and positioned low relative to the ground surface. White, comb-like spines lie against the surface and shelter the stem. Flowers develop in whorls around the apex. Whitish, berry-type fruits remain embedded between the tubercles or are expelled whole. The position of successive whorls allows the approximate year of fruiting to be determined. [Peters et al. 2009, pp. 537–538, Fig. 1]

Serotiny and seed retention

Fruits that are not expelled gradually release seeds through an opening in the upper part. Their contents decrease with age, and empty fruits remain as dry remnants. In a sample of 615 fruits from 20 plants, seeds were rarely found in fruits older than four years. In the first year, a mean of 42.6% of seeds remained in retained fruits. This mode of dispersal distributes part of the seed supply over successive seasons. [Peters et al. 2009, pp. 538–539]

Seeds recovered from fruits showed mean germination of about 46% on agar at 25°C with a twelve-hour photoperiod, assessed after 30 days. In this sample, no significant decrease in germination with fruit age was found. The result describes a viable reserve held on the plant, taking the test conditions into account. [Peters et al. 2009, pp. 538–539]

Water and establishment of the next generation

In a population of 81 marked adult plants, no expulsion of whole fruits was recorded in the dry 1997 season. In the wet 1998 season, 21.5% of new fruits were expelled. An experiment with 30 adult plants in a greenhouse confirmed that fruit expulsion increased with watering intensity. Fruits of the youngest cohort were actively expelled. [Peters et al. 2009, p. 538–540]

The number of seedlings surviving the next dry season was estimated at 17 in the first season and 95 in the second, over 238 m². Their proportions of the estimated numbers of released seeds were 0.47 and 2.38‰. This approximately fivefold increase in establishment success coincided with the wetter season. Serotiny and expulsion of new fruits create two complementary dispersal rhythms. [Peters et al. 2009, pp. 539–540, Table 1]

Documentation of sowing material

A retained fruit may contain seeds from an earlier season. The fruiting year, collection date and extraction method therefore matter in sowing records. A plant that retains a fruit within its stem may gradually lose its contents. A dry fruit remnant and a fruit still containing seeds are distinct states of the material. [Peters et al. 2009, pp. 538–539]

Stones and seedling establishment

In the field study by Peters, Martorell and Ezcurra, the distribution of Mammillaria pectinifera was positively associated with stones at least 20 cm in diameter. The criterion for plant distance from a stone was less than 2 cm. The association was statistically significant, p = 0.0010. Distribution relative to shrubs was statistically neutral, p = 0.7919. The authors also observed numerous plants beside smaller stones, outside the category included in this test. [Peters et al. 2008, p. 595–596, tabela 1; p. 599]

A separate experiment compared three-day-old and six-month-old seedlings on exposed ground, under artificial shade and beside a stone at least 30 cm in diameter, with and without protection from herbivores. All seedlings in the youngest group eventually died. Older seedlings survived longest beside a stone, especially with protection from herbivores. The result shows how plant stage and immediate surroundings affect establishment success in the field. [Peters et al. 2008, p. 596–598, ryc. 1–2]

Surviving plants beside stones reached a mean height of 5.84 ± 0.14 mm, compared with 5.30 ± 0.18 mm under artificial shade. These are means ± standard errors, p = 0.026. The comparison concerns surviving older seedlings. The authors link the beneficial effect of a stone to the combination of milder conditions near the substrate and access to light needed by the small photosynthetic surface of a partly sunken stem. Temperature, water balance and gas exchange remain interpretations of the mechanism in this experiment, while the measured results comprise plant survival and size. [Peters et al. 2008, pp. 598–600]

Related articles

Materials from the author's archive

The species also appears in Konrad Szychowski's private material archive. [Hernández-Oria et al. 2003, file p. 12] [Rodríguez Ortega and Franco 2001, file p. 6] [Kreuzinger 1935, file p. 10]