Short answers, pulled from the story.
A xerophyte is a plant species with adaptations that allow it to survive in environments with little liquid water. Common examples include cacti, pineapple, Agave americana, and certain gymnosperm plants, as well as resurrection plants such as the Rose of Jericho (Anastatica hierochuntica) and Haberlea rhodopensis.
Xerophytes conserve water through a range of structural and chemical adaptations, including reduced leaf surface area (such as cactus spines), thick waxy cuticles, tomentose (hair-covered) surfaces that trap moisture, inverted stomatal rhythms that keep stomata closed during the hottest part of the day, CAM photosynthesis that collects carbon dioxide at night, and the ability to store water in swollen stems, roots, or leaves.
Crassulacean acid metabolism (CAM) is a photosynthetic pathway in which plants open their stomata at night to collect and store carbon dioxide, then use it for photosynthesis during the day with stomata closed to minimise water loss. Plants that employ CAM include the pineapple, Agave americana, Aeonium haworthii, and Sansevieria trifasciata.
Resurrection plants are xerophytes that can survive desiccation of their tissues, losing more than 80% of their water content and effectively shutting down metabolism, then reviving when water returns. During desiccation, levels of the sugars sucrose, raffinose, and galactinol rise and are thought to protect cells from damage. Examples include Haberlea rhodopensis, Ramonda serbica, Anastatica hierochuntica (the Rose of Jericho), and Craterostigma pumilum.
Xerophytic shrubs such as Caragana korshinskii, Artemisia sphaerocephala, and Hedysarum scoparium are dispersed across degraded land in northwest China to stabilise sand dunes and restore vegetation. Haloxylon ammodendron and Zygophyllum xanthoxylum also contribute to fixed dune formation. These plants are additionally edible to grazing animals including sheep and camels.
Dudleya brittonii has a white chalky epicuticular wax coating that holds the highest ultraviolet light reflectivity of any known naturally occurring biological substance. This reflective surface reduces the amount of solar energy absorbed by the plant, limiting transpiration and heat stress.