Grusonia moelleri

Growth form and comparative characters

Branched segments form low clusters. In the 2014 morphometric comparison, mean plant width was about 29 cm, and segments averaged 41 mm long and 25 mm wide. These are values from one sample examined, used for comparison with the larger G. halophila (both taxa belonged to Corynopuntia in the paper). [Donati 2018]

The author identified differences in segment size and areole density, also visible in young plants. For flowers and fruits, pericarpel length is helpful, averaging about 34 mm in G. moelleri and 58 mm in G. halophila in this sample. The full comparison, with standard errors, appears in the G. halophila profile. [Donati 2018]

Habitat and variation

The species belongs to the flora of the Chihuahuan Desert region. In Coahuila, populations on clay-gypsum substrates were compared near saline depressions occupied by G. halophila. Geographical variation in G. moelleri morphology was observed, making it difficult to establish species boundaries from one dimension or a photograph of a single segment alone. [Bárcenas and Hernández 2022] [Donati 2018]

Chromosomes and regeneration

The G. moelleri material analysed by Donati was diploid, 2n = 22. Plants intermediate in appearance between the two species were selected separately, and 2n = 22 or 44 was found among them. These results describe cytotypes in the sample and form part of the discussion of reproductive isolation and morphological variation. [Donati 2018]

Detached and rooted stem fragments were found at the site. Their number per plant was lower than in G. halophila. Branching architecture, ease of terminal-segment detachment and conditions of substrate contact matter in this comparison. [Donati 2018]