Name and plant variation
Cephalocereus apicicephalium is accepted by POWO and is native to Oaxaca and Chiapas. The database, checked on 16 October 2026, also includes C. nizandensis and C. totolapensis among its synonyms. In the publications, these names denoted separately recognized groups of populations. Retaining them alongside research findings identifies the part of the currently more broadly circumscribed species to which an observation applies. [2-WWW]
The studied plants had columnar, ribbed stems branching near the base and an apical flowering region termed a pseudocephalium. Under the historical concepts of C. apicicephalium and C. nizandensis, shorter and more extensively branched plants were described. The name C. totolapensis referred to taller plants with fewer branches and annular remnants of previous flowering events. These descriptions apply to the material distinguished in those treatments. [Bárcenas-Argüello et al. 2010] [Tapia et al. 2017]
Rocky microhabitats in the Tehuantepec basin
The 2010 study covered eleven populations in the Tehuantepec basin. The authors compared bedrock, material accumulating near the roots, slope position and tissue mineral composition. In populations described as C. apicicephalium, plants occupied limestone outcrops containing quartz. Roots extended near the surface and entered cracks where organic debris accumulated. The crack system allowed water to drain. [Bárcenas-Argüello et al. 2010]
Plants identified as C. nizandensis grew in cavities in metamorphosed calcareous rocks. Water and organic matter accumulated in these cavities. By contrast, populations called C. totolapensis occupied substrates derived from andesite, siltstone and mica schist, among other materials. A layer of fine-textured soil was more important there. Different combinations of slope and stoniness allowed excess water to drain. [Bárcenas-Argüello et al. 2010]
This distribution produced separated patches of suitable substrate in the landscape. A change in rock type or in the properties of material around the roots could mark the distribution boundary of a studied population. The findings apply to particular localities in Oaxaca and the names adopted in 2010. In the current species account, they illustrate variation among populations. The habitat data describe rock, drainage and rooting position together. [Bárcenas-Argüello et al. 2010] [2-WWW]
Minerals within the tissues
Diffraction analyses identified weddellite, a hydrated form of calcium oxalate, in the tissues. Microscopy revealed varied crystal aggregates. Other elements were also detected, and the authors associated these inclusions with differences in crystal shape. The presence of the crystals was an observation. Their possible role in reducing excess radiation or affecting herbivores remained a proposed functional explanation requiring direct experiments. [Bárcenas-Argüello et al. 2010]
Plant-derived biominerals made up a small proportion of the mineral fraction of the sampled ground material. The authors concluded that their accumulation in this system had a limited effect on substrate mineral composition. Cactus tissue structure and rock properties therefore represent distinct levels of description. Studying them together helps explain population distribution while retaining the local scope of habitat characteristics. [Bárcenas-Argüello et al. 2010]
Related articles
Materials from the author's archive
The species also appears in Konrad Szychowski's private material archive. [Martínez et al. 2001]
Synonyms and names in the literature
Cephalocereus nizandensis · Cephalocereus totolapensis · Neodawsonia apicicephalium · Neodawsonia nizandensis · Neodawsonia totolapensis · Neodawsonia apicicephalium subsp. totolapensis [2-WWW]