While many desert plants are reasonably safe to own and display, some come with a great deal of risk attached--risk to both people and to pets. Families with young children, those with members who have strong allergic reactions and those with animals--livestock or pets--may want to avoid certain plants out of caution. Other plants should be avoided for good reason, posing a serious risk to health and safety.
Cacti have developed sharp spines as a defense against damage from birds and animals. Thin, small diameter spines can at times be nearly impossible to see and difficult to remove. A pet or small child may have no way to communicate the presence of an imbedded needle, other than signs of general distress or favoring the part of the body affected.
According to the Cactus and Succulent Society of Australia, most members of the genera Echinocactus and Ferocactus have a reputation for troublesome and harmful spines. These cacti are often barrel-shaped and carry spines with hooked tips, while the genus Opuntia carry barbed spines. The society warns that the smallest spines of the Opuntia are able to become airborne and lodge in the eyes and mouths of humans and pets, causing a great deal of pain.
As with any plant--particularly wild plants--you should know the proper method for identification and preparation before consuming any part. Some cacti are edible, while others can be poisonous if not prepared in the right manner. As the Cactus and Succulent Society of Australia warns, some varieties of cacti have hallucinogenic and narcotic properties.
Agave plants produce large thorny spikes with ends like needles. These are a hazard to those who may come into causal contact with the plant--a particular danger when agave is used as a landscape feature. Agave juice or sap can cause irritation and even acute dermatitis. In particular, the sap of Agave americana is known to contain irritants in the form of calcium oxalate crystals, acrid oils and saponins, according to the Journal of the American Academy of Dermatology.
Euphorbia produce a milky white sap, a tell-tale sign of danger. The sap is caustic, an irritant to skin, but a particular danger to the eyes of humans and pets alike. Because even the vapor from the sap can cause a reaction in the respiratory system if inhaled, the Cactus and Succulent Society of Australia suggests handling the plant in a ventilated space or outdoors and upwind.
According to The Amateurs’ Digest, depending on the specific member of the genus, reactions to the latex (the sap) can run the gamut from blisters on the skin to deformities in animal offspring to death. The intensity of reactions varies depending upon the species of Euphorbia and the individual, but is of more concern for those who have an allergy to latex. Spurge and poinsettia are common examples of Euphorbia.