Austrocylindropuntia subulata

Leaf structure

In anatomical descriptions, leaves reach about 12 cm in length and 6 mm in diameter. Their cross-section is approximately round, with retained traces of dorsiventrality. Vascular bundles are asymmetrically arranged, and the leaf may be flattened at its base. Beneath the epidermis lies palisade parenchyma of short, broad cells. Deeper inside is compact non-palisade parenchyma that also contains chloroplasts. [Ozerova and Timonin 2020b]

Cells in both zones store water. No chlorophyll-free hydrenchyma was distinguished in the material studied. Mucilage idioblasts, sometimes very large, are scattered among assimilatory cells. Longitudinal rows of cells are associated with the growth pattern of the cylindrical leaf and are more visible in longitudinal than transverse sections. [Ozerova and Timonin 2020b]

Gas exchange during drought

In Nobel and Hartsock's experiment, day and night temperatures were 25/15°C and each phase lasted 12 hours. In well-hydrated leaves, about 98% of daily CO₂ uptake occurred during the day. After seven days of drought, nocturnal uptake predominated. After fourteen days, the daytime leaf balance was zero and a small positive assimilation remained at night. In stems, positive uptake occurred at night from the outset and weakened with drought. [Nobel and Hartsock 1987]

Later simultaneous measurements of gas exchange and acidity confirmed the combination of atmospheric CO₂ uptake with nocturnal recycling of respiratory carbon. Increasing tissue acidity and nocturnal CO₂ entry from the air therefore describe two related but separately measured components of CAM metabolism. [Martin and Wallace 2000]

Expansion beyond the natural range

In northeastern Algeria, fourteen populations at twelve places were recorded in 2016–2021. Plants exceeded 2 m in height, flowered and fruited, and the largest clusters occupied areas including coastal dunes. The observations document the ability to persist and expand in a Mediterranean climate. They provide data on particular introduced populations. [Sakhraoui et al. 2022]

Mokra zgnilizna

In Iran, Klebsiella aerogenes was isolated from wet, darkening stem rot. Identification was supported by the rpoB gene sequence, and inoculating healthy plants produced symptoms and allowed the bacterium to be isolated again. The study establishes the cause of the described disease case. The authors did not conduct experiments on the efficacy of plant-protection products. [Basavand et al. 2020]

Studies of applications of this species are presented in a separate account in the “Biotechnology and applications” section. [Meftah et al. 2024]