Pediocactus peeblesianus

One account covering the former division

POWO accepts Pediocactus peeblesianus as one species occurring from southwestern Utah into Arizona. Older literature includes the names Navajoa peeblesiana, Neonavajoa peeblesiana, Utahia peeblesiana and Toumeya peeblesiana. Subspecies fickeisenii and the typical subspecies are synonyms of the same species in this treatment. In publications, the epithet of the first group was also written fickeiseniae or fickeiseniorum. [2-WWW] [Baker and Cloud-Hughes 2022, POWO, as of 11 October 2026. Baker and Cloud-Hughes, pp. 299–303, 313–314]

Corky spines on a small stem

The grey-green stem is spherical, obovoid or flattened. Flora of North America gives a height of 2–6.5 cm and width of 1.5–5.5 cm. Spines are whitish or grey, soft and spongy in their thicker part, with a harder tip. There are usually 3–7 radial spines, 2–9 mm long. A central spine may be absent or reach 5–18 mm. Flowers are creamy yellow or yellow-green, 1.5–2.5 cm in diameter. Seeds have a wrinkled dark surface. [Heil and Porter 2003a, Flora of North America, P. peeblesianus, scope of formerly described subspecies]

What the morphometric analysis compared

Baker and Cloud-Hughes studied seventeen stem and spine traits. In April and May 2014, they collected measurements from 233 P. peeblesianus plants in eight populations. They added 90 P. sileri specimens from three populations as a comparison group. The total of 323 concerns both species. Documentation relied on observations and photographs of field plants, without collecting them as herbarium specimens. [Baker and Cloud-Hughes 2022, p. 303–309, tab. 1, 4]

Simultaneous analyses of many traits showed substantial overlap between former groups within P. peeblesianus. Statistically defined groups did not provide a practical, geographically consistent taxonomic division. At the same time, P. sileri remained clearly distinct in the material studied. The result concerns subspecies boundaries in the first species while retaining the distinctness of the second. [Baker and Cloud-Hughes 2022, p. 305–313, tab. 4–6]

Plant size as part of the explanation of variation

Four traits were associated with stem diameter, tubercle height, distance between areoles, length of the longest central spine and its angle. Comparing a small plant with a large one therefore also includes developmental changes. Spine proportions alone do not define a sharp boundary between former subspecies. [Baker and Cloud-Hughes 2022, p. 309–313, tab. 7]

The authors interpreted small flowering plants on shallow substrates as neotenic, retaining some juvenile features despite attaining reproductive capacity. This explanation agrees with the observed relationship to size and site conditions. The link with soil depth was assessed in the field, rather than by experimentally moving plants between substrates. [Baker and Cloud-Hughes 2022, p. 311–314]

Related articles

Materials from the author's archive