Germination of Coryphantha durangensis
Muro-Pérez and coauthors used seeds of Coryphantha durangensis collected in April 2009 from at least ten plants in Cañón de Fernández in Durango. Surface placement was compared with burial at a depth of 0,5 cm. The second factor was soil collected either beneath mesquite or from open ground. Each of the four treatments comprised five replicates of 20 seeds, giving 100 seeds of this species per treatment. [Muro-Pérez et al. 2014, pp. 345–346]
After one month, 96% of seeds germinated on the surface of soil from beneath mesquite, compared with 56% on the surface of soil from open ground. After burial, the results were 2% and 0% respectively. The experiment demonstrated both a strong effect of seed position and a difference between soils under surface sowing. [Muro-Pérez et al. 2014, p. 346, Fig. 1B]
Significance of covering the seed
The authors linked poor germination of buried seeds partly to restricted light access. Burial itself, however, changes several conditions at once, including substrate contact and conditions around the seed. The study did not separate light from the other consequences of covering. The direct conclusion concerns the advantage of surface sowing in the system used. [Muro-Pérez et al. 2014, pp. 346–348]
The trial ended at germination. It did not determine subsequent seedling survival or the viability of seeds remaining underground. The very small number of seedlings emerging after burial can therefore be described as restricted germination within one month. Persistence of any seed bank would require following the seeds' subsequent fate. [Muro-Pérez et al. 2014, pp. 345–348]
Five-year-old Coryphantha maiz-tablasensis
Guerra-Coss and coauthors studied a different developmental stage. Their material comprised 80 Coryphantha maiz-tablasensis grown from seed and maintained in a greenhouse for five years. They were planted in San Luis Potosí beneath mesquite canopies of Neltuma laevigata and on adjacent open ground. In each habitat, 20 plants served as controls and 20 were warmed in open-top chambers. Groups of four plants were placed in five study plots. [Guerra-Coss et al. 2025, article 105461, Sections 2.1–2.2]
After planting, each plant received a single 20 ml dose of water and was then left without further watering. Control plots were surrounded by mesh restricting herbivore access. Observations lasted 266 days, from 26 April 2024 to 17 January 2025. Air temperature was measured 20 cm above ground and soil moisture at a depth of 7,6 cm. Survival was thus compared with microclimate within the experiment. [Guerra-Coss et al. 2025, article 105461, Sections 2.2–2.3]
Survival beneath mesquite and in the open
Warming raised mean air temperature in the open habitat by 1,4°C and maximum temperature by 4,1°C. Beneath canopies, the increases were 1,0°C and 2,8°C. In the mesquite habitat, 100% of control plants and 95% of warmed plants survived. In the open, 90% of controls survived and none of the warmed plants did. Each percentage refers to a group of 20 plants. [Guerra-Coss et al. 2025, article 105461, pp. 4–5 PDF, Table 2, Fig. 4]
Nurse plants often alter several components of a microhabitat. In this experiment, soil beneath canopies contained less water on average than soil in the open. The canopies, however, reduced radiation and air heating. Better survival beneath trees thus occurred despite lower measured soil water availability. The authors linked protection primarily to milder heat and light stress. Stem temperatures and damage to the photosynthetic apparatus were not measured. [Guerra-Coss et al. 2025, article 105461, pp. 4–6 PDF, Table 2, discussion]
Significance of the developmental stage
In the experiment with C. durangensis, soil from beneath mesquite was used as sowing material. Shade cast by a living tree was not studied. In the experiment with C. maiz-tablasensis, the living canopy changed the surroundings of young plants, and the assessed outcome was their survival after transfer from a greenhouse. The studies describe separate effects of soil and nurse plants at different stages. [Muro-Pérez et al. 2014, pp. 345–348]
According to the monograph, an adult C. maiz-tablasensis has much of its stem underground and a developed taproot. [Dicht and Lüthy 2005, p. 153] The experiment nevertheless used a particular batch of five-year-old plants. The reported differences in temperature and survival describe the sensitivity of this material to field conditions. They allow assessment of the protective effect of canopies at the studied site without defining a universal temperature tolerated by all plants of the species. [Guerra-Coss et al. 2025, article 105461, Section 2.2 and discussion]
Effect of seed burial in different soils on the germination of three specially protected cactus species
Muro-Pérez G., Jurado E., Flores J., Sánchez-Salas J., Effect of seed burial in different soils on the germination of three specially protected cactus species, The Southwestern Naturalist, 2014, 59(3):344-348, doi: 10.1894/MLA-06.1
A germination experiment on Coryphantha durangensis, Peniocereus greggii and Echinocereus longisetus. It compares seeds on the surface and beneath a soil layer, in substrate from beneath mesquite and from open spaces. It shows how germination depends on seed position and soil origin, with different species responses.
Do nurse plants enhance cactus survival under global warming? Experimental evidence from Coryphantha maiz-tablasensis, a threatened species
Guerra-Coss F. A., Flores J., Aragón-Gastelum J. L., Badano E. I., Ramírez-Tobías H. M., Do nurse plants enhance cactus survival under global warming? Experimental evidence from Coryphantha maiz-tablasensis, a threatened species, Journal of Arid Environments, 2025, 231:105461, doi: 10.1016/j.jaridenv.2025.105461
A field warming experiment on five-year-old Coryphantha maiz-tablasensis plants grown from seeds. It compares survival beneath Neltuma laevigata canopies and in open spaces, and records temperature, light, rainfall and soil moisture. It shows the effect of microhabitat on young plant responses in one season.
Coryphantha: Cacti of Mexico and Southern USA
[Dicht R. F., Lüthy A. D., Coryphantha: Cacti of Mexico and Southern USA, Springer, Berlin–Heidelberg, 2005, s. VIII + 200, doi: 10.1007/b138100]
A monograph of the genus with species descriptions, keys, photographs and habitat documentation. It discusses tubercle groove development, spine variation, roots, flowers, fruits and seeds. It includes an internal classification, analysis of former names and a chapter on cultivation practice.