Pereskia (2023)

The Father of Cacti?

Scientists believe cacti evolved from Pereskia. The genus exhibits traits critical to the development of stems as photosynthetic organs.

By Bob Williams (February 2023)

If you ask most people to describe cactus, they first say they’re spiny. Then they’re succulents. Next would be that they’re leafless. This description is basically correct, except for 17 species of the genus Pereskia.

Although Pereskia does not resemble other cacti in its overall morphology, close examination shows spines developing from areoles, and the distinctive floral cup of the cactus family. The plants are shrubs, trees or climbing vines, with maximum heights varying between 3 and 10 m. Unlike the great majority of species of cacti, they have persistent leaves. Their succulent leaves are longer than wide. In habitat, they are found in drier forests from South America northward to Mexico and on most Caribbean islands.

So why do scientists believe that cacti evolved from Pereskia, besides from the similarities described above? This genus has stem stomata and exhibits delayed bark formation, two traits that are critical in the development of the stem as a photosynthetic organ. In habitat, pereskias exhibit some weak CAM (Crassulacean acid metabolism) respiration. This is where respiration occurs at night, which reduces water loss.

Put this all together, and these plants are considered the best living representation of the “ancestral cactus.” As these plants were exposed to drier climates, leaves were lost, stems got thicker, shallow roots spread out over a wide area, and CAM became highly efficient, resulting in the cacti we grow and love.

In the wild, these plants are typically found among other trees and shrubs, and their presence is not immediately apparent. In flower, the shrubs can be quite brilliant, with individual flowers that are reminiscent of a wild rose, hence the common name sometimes used: rose cactus. Flowers are normally pink to purple but can be white.

It is rare for a cactus to be edible and have medicinal value, but pereskias have both. The leaves and fruits are edible, containing 20 to 30 percent protein in the dry leaf matter, iron and other nutrients. The plants are a popular vegetable in parts of the Brazilian state of Minas Gerais under the name of ora-pro-nóbis, a phrase from the Latin mass meaning pray for us. The leaves are used in green salads or can be cooked. In rural Brazil, the leaves, stems and fruits are also used for food for animals. The flavor of the fruit has been likened to that of a cranberry or gooseberry.

The leaves of P. bleo have been traditionally used to treat cancer, hemorrhoids, hypertension, diabetes, infections, gastric pain, headache, ulcer, and inflammatory conditions like rheumatism and asthma. Indigenous Colombians have used P. bleo to neutralize the effects of snakebites, relax spastic muscles and alleviate muscle aches. The fruits of P. aculeata show expectorant and anti-syphilis properties.

Pereskias are easy to propagate from cuttings or seeds. Cuttings should be planted immediately – or just put in a jar of water.

These plants are easy to grow and said to be nearly indestructible. They require full sun or light shade (but withstand dense shade) and well-drained media, preferably rich neutral organic soils (but may tolerate acidic ones). Pereskias are suited to tropical or subtropical climates, but may survive very light, short frosts.

In areas where the plants can grow outside all year, they are used in landscaping as a hedge. In parts of Florida, members of the Pereskia genus are considered nuisance plants. South Africa has declared pereskias invasive species.

Pereskia species are fast growers that will become large in just a few years. They are long-lived plants that, once established, don’t require frequent repotting. Also, overwatering is not a big issue for them. New growth usually begins in late March and continues through September. Do not let the plants stand in water for an extended period of time. Keep them almost completely dry in winter.

Pereskias are drought-resistant, but leaves drop during drought periods. They are not winter-hardy in our area. When grown in a pot, prune them to keep their shape and promote branching. They are very easy to propagate from cuttings or seeds. Contrary to most other cacti, Pereskia cuttings should be planted immediately without a dryout period. You can also just put the cuttings in a jar of water. They are frequently used as grafting stock.

These plants are easy to find and not extremely expensive. If your cacti are clamoring to know who their daddy is, buy a pereskia and introduce them.

Sources

Hindawi – A Review of Botanical Characteristics, Traditional Usage, Chemical Components, Pharmacological Activities, and Safety of Pereskia bleo – https://www.hindawi.com/journals/ecam/2014/326107/
Missouri Botanical Garden Plant Finder – Pereskia grandifolia – https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=369153
ScienceDirect – Wound-Healing Properties and Mucilage Content of Pereskia aculeata From Different Substrates – https://www.sciencedirect.com/science/article/pii/S0102695X15000162
North Carolina State University – North Carolina Extension Gardener Plant Toolbox – https://plants.ces.ncsu.edu/plants/pereskia/
Wikipedia – https://en.wikipedia.org/wiki/Pereskia