Opuntia microdasys is one of the most recognisable cactus species on the planet, and its relatively small stature has made it one of the most popular houseplants there is. Commonly known as Bunny Ears, it only grows up to 1m tall in nature, and often maxes out at 60cm, growing sideways as much as it grows up. It is native to the Chihuahuan Desert in Mexico, where it provides shelter for birds, insects and small mammals, as well as pollen, nectar and fruit for invertebrates. Unfortunately, O. microdasys has become an invasive species in other parts of the world, including South Africa, Australia, Spain, Italy, Malta and Kenya, creating dense thickets that can crowd out native species.
The species name ‘microdasys’ translates as ‘small and hairy’: the plant is made up of flattened, paddle-shaped stems called cladodes that grow one on top of another in a seemingly precarious pattern that resembles a toddler’s attempt at making a tower from wooden or plastic blocks.
Each cladode is covered with very fine hairs that are invisible to the naked eye, but give them a velvety look; they are also dotted with yellow spots, which may look as plush as a fluffy bunny, but contain the plant’s secret weapon: glochids. Each dot is an areole; a bump that acts as an anchor for around 100 glochids. These tiny hairlike structures are called ahuates in Spanish. They may look harmless, but stick one under an electron microscope and their purpose becomes clear. As The Gardeners’ Chronicle put it in an article in 1903, Bunny Ears glochids may look inoffensive but are “of the most dangerous character”.
Each glochid measures around 1–3mm long, with a pointy tip. Down the sides of the top third or so of each glochid are minuscule barbs. Although glochids detach from the areole with ease, once one is lodged in the skin, its barbs act like hooks and make them hard to remove. When lodged in the skin and, even worse, the eyes, glochids cause skin irritation and conjunctivitis. This isn’t limited to humans, either. In Mexico Opuntia microdasys is called nopal cegador – blind prickly pear – because the glochids have been known to hurt the eyes of grazing livestock. So, if you own a Bunny Ears, take care when placing plants to ensure they cannot be reached by children, pets or any unsuspecting person, and handle them only when wearing extremely thick leather or rubber gloves, or surround the plants with a thick layer of rolled up newspaper. Of course, glochids have not evolved to wind up cactus growers, they protect the plant from being munched by herbivores, and assist with another water-saving function, too. O. microdasys collects water droplets from fog via the glochids which channel the water towards the plant down minuscule grooves.
The species was first described by European botanists in 1827, and caught on quickly in cultivation, despite its drawbacks, which include the glochid issue, but also the fact that, when grown as a houseplant in a pot, O. microdasys is unlikely to flower, as it needs open ground to stimulate development of the lemon-yellow flowers.
Look out for cultivars of Opuntia microdasys with pure white, rusty red or brown glochids, or if you want to avoid injury, opt for the extremely popular cultivar ‘Angel Wings’ which lacks the barbed glochids of the species.
For more on the Bunny Ears cactus, check out my book Legends of the Leaf: Unearthing the Secrets to Help Your Plants Thrive, which includes a whole chapter on this plant as well as other succulents including Crassula ovata and Curio rowleyanus.
https://www.janeperrone.com/books/#legends
Text and photos by Jane Perrone
No part of this article may be reproduced without permission. Copyright BCSS & the Author 2024
