Pitahaya sp. Plant on a support
Fleshy stems grow along a support. Adventitious roots are shown on their surface. Buds, a flower and a fruit appear on the same plant as illustrative developmental stages. [Crane and Balerdi 2006] [Korotkova et al. 2017]
Illustrative image generated with AI and supplied by the site author. The label Pitahaya sp. refers to the shared appearance of this group of plants. Proportions and details are schematic.
Enlarge plate ↗Name and distribution
Selenicereus monacanthus (Lem.) D.R.Hunt is the name accepted in POWO. Hylocereus monacanthus and H. polyrhizus are synonyms. The database records a native range from Nicaragua to Trinidad and Peru. The historical name polyrhizus remains important when searching horticultural, chemical and biotechnological studies. [2-WWW]
Fruits and material studied
Cohen and Tel-Zur’s material included diploid accessions with red peel and purple pulp. They compared these with lines produced by chromosome doubling. The account concerns identified accessions and derived lines, allowing the species, cultivar and experimental material to remain distinct. [Cohen and Tel-Zur 2012, p. 346–351]
The path of self and cross pollen
Compatibility depends on genotype. Li and colleagues examined the self-incompatible Selenicereus monacanthus cultivar ‘Hongshuijing’. Its own pollen germinated on the stigma, but the pollen tubes stopped approximately halfway along the style. Pollen from ‘Dahong’ progressed further to the ovary. Fruit production therefore calls for material with a known breeding system and a partner providing compatible pollen during flowering. [Li et al. 2022, Li et al. 2022 p. 4–8, Cohen and Tel-Zur 2012 p. 346] [Cohen and Tel-Zur 2012, Li et al. 2022 p. 4–8, Cohen and Tel-Zur 2012 p. 346]
In the study of ‘Hongshuijing’, a style glycoprotein extract inhibited the growth of self pollen tubes in culture. Transcriptomic analyses identified S-RNase and F-box genes as candidates associated with pollen recognition. Their roles in the detailed mechanism remain hypotheses requiring functional validation. [Li et al. 2022, p. 5, 7–8, 15–18]
Polyploid breeding lines
Cohen and Tel-Zur studied lines obtained by chromosome doubling. From diploid Selenicereus monacanthus, they produced tetraploids that formed fruit after self-pollination. This was accompanied by changes in pollen size, pollen viability and seed traits. The result shows that chromosome-set number can alter pollen–pistil compatibility. [Cohen and Tel-Zur 2012, p. 346–353]
Metaxenia and ripening time
Mizrahi and colleagues pollinated clone 89-028, reported as Hylocereus polyrhizus and linked in this atlas to Selenicereus monacanthus. Pollen source affected ripening time and some fruit traits. In Table 1, mean ripening time was 31.4 days with pollen from the Hylocereus group, 36.1 days with S. grandiflorus pollen and 51.0 days with S. megalanthus pollen. Four fruits were assessed in the last treatment, versus 66 and 38 respectively in the others. The effect concerns a particular clone and greenhouse crossing combinations. [Mizrahi et al. 2004, pp. 469–471, Table 1]
The tested genotype and the compatibility mechanism
Li and colleagues combined microscopic pollen-tube observations with gene-expression analysis after pollination of ‘Hongshuijing’. Comparing self- and cross-pollen identifies the stage at which growth is arrested in the style. Genes selected from expression data remain candidates for further experiments. Tel-Zur’s review of the breeding programme shows the importance of testing clones and their mutual compatibility during selection. Retaining cultivar identity allows the result to be used within its scope rather than extended to every red-fleshed plant. [Li et al. 2022, Li et al. 2022 pp. 4–8, 15–18; Tel-Zur 2022 pp. 2–8] [Tel-Zur 2022, Li et al. 2022 pp. 4–8, 15–18; Tel-Zur 2022 pp. 2–8]
Related articles
Materials from the author's archive
The species also appears in Konrad Szychowski's private material archive. [Schumann 1890, file p. 17, 20]
Synonyms and names in the literature
Hylocereus monacanthus · Hylocereus polyrhizus · Cereus monacanthus · Cereus polyrhizus [2-WWW]