Cylindropuntia fulgida var. mamillata

Name and habit

POWO accepts variety rank for Cylindropuntia fulgida var. mamillata. Other accounts treat it as forma or subspecies mamillata, and historically as Opuntia mamillata and O. fulgida var. mamillata. The natural range includes Arizona and northwestern Mexico. [2-WWW]

Mature plants have a shrubby or small-tree habit, often about 1–1.5 m tall. Segment armature is sparser than in the typical variety fulgida. Further flowers develop from areoles of older fruits, leaving characteristic fruit chains on hanging branches. [Bobich 2005]

Segments and fruits as propagules

Bobich compared two clusters near Oracle, Arizona, with different plant-size structures. In the field, he found daughter individuals near plants from almost all height classes. Terminal segments were the most commonly rooted fragments, although fruits and larger detached pieces also formed roots. [Bobich 2005]

In the greenhouse, rooting capacity of material from both clusters was similar after 20 weeks. Water availability changed the rate of the process. After an initial 12 weeks of drought, segments used the later watering period better than fruits, which the author associated partly with greater water and organic-compound reserves in the stem. [Bobich 2005]

Cluster structure and competition

The cluster with larger plants had fewer young individuals and more ground occupied by vegetation, debris and adult cholla branches. The author considered competition for light, water and space as an explanation of weaker regeneration. Relatedness of small plants to the nearest adults was assessed from position and structure, so the designation of offspring is a field assignment here. [Bobich 2005]

Invasive populations and Dactylopius scale insects

At two Queensland sites, biological control of the invasive variety by the “cholla” lineage of Dactylopius tomentosus was studied. Insects spread from release plants, and live-cactus density fell sharply. At one site, heavy rainfall and flooding delayed scale-insect establishment and required repeat release. The 2023 publication documents an Australian field programme and its course. [Jones et al. 2023]