PlantaeDB Logo
Login Sign-up

Genus Pachyphytum in Family Crassulaceae

In botanical taxonomy, a genus (plural genera) is a rank used to group closely related species within a family. In the hierarchy, genus sits below family and above species.

Genera are defined by shared morphological, anatomical, and genetic characteristics (for example, features of flowers, fruits, seeds, or leaves) that indicate a close evolutionary relationship among the species they contain.

Each genus can include one or more species. Examples include Rosa (roses) and Solanum (nightshades, including tomato and eggplant).

Do you wish to read more about plant taxonomy? Click here!

Genus Description

Suggest a correction!

Pachyphytum (Link, Klotzsch & Otto) is a small genus of perennial succulent herbs in the family Crassulaceae (order Saxifragales). About 13 species are currently accepted (POWO, 2024; WFO, 2024). The genus is endemic to the Mexican highlands and Baja California, occupying arid limestone cliffs, volcanic outcrops and xerophytic scrub at elevations of 1500–3000 m. The type species is Pachyphytum oviferum Link.

Diagnostic morphology centers on compact rosettes of thick, fleshy, obovate to spatulate leaves densely covered in waxy farina that gives a bluish hue. Leaves are sessile, lack stipules, and have a simple, unbranched vascular system typical of Crassulaceae. Inflorescences are terminal thyrses or racemes bearing numerous small, star‑shaped flowers; each flower has five to seven free petals, five sepals, ten stamens, and a superior, apocarpous ovary with free carpels. The fruit is a follicle dehiscing along a single suture, releasing minute seeds with a short funicle.

Species richness peaks in the Sierra Madre Oriental and the Trans‑Mexican Volcanic Belt, with several narrow endemics such as P. glaberrimum restricted to single mountain ranges (Hernández et al., 2022). Habitats range from limestone cliffs in Chihuahua to basaltic outcrops in the Sierra Madre Occidental; the genus exemplifies high desert and montane xeric adaptation.

Pollination is presumed to involve small bees and flies, though observations remain sparse; seed dispersal is primarily ballistic, with follicles ejecting seeds a few centimeters from the parent (Kim et al., 2010). Chromosome counts for P. oviferum are 2n = 34, indicating a base number x = 17 (Kim et al., 2010).

Molecular phylogenies consistently recover Pachyphytum as a distinct clade within the subfamily Sempervivoideae (Mort et al., 2011; Liede‑Schumann et al., 2019). Some treatments still treat the group as a subgenus of Echeveria (Berger, 1908; Browicz, 2019), showing lingering circumscription debate. Current consensus based on plastid and nuclear data supports generic status for Pachyphytum (POWO, 2024).

The genus is prized in horticulture as ornamental succulents for rock gardens, containers and xeriscapes; none of the species are considered invasive. Conservation assessments indicate that habitat loss from agriculture and quarrying threatens several endemics, while demographic and genetic data remain scarce. Future work should prioritize population surveys and integrative taxonomy to clarify species limits and guide conservation actions.

Pick a Species to see its components: