Beauty among the barbs

For the past five years it has been a distinct pleasure to volunteer my time at the Conservatory and Botanic Collection at the University of Minnesota. Within those greenhouses I quickly learned there are many dangerous plants. For example, imagine having to relocate the pot of a 5-foot 30 pound cactus covered in 2-inch needles sharp enough to pierce almost any glove. As another example, imagine dividing and repotting an agave measuring 4 feet in height and diameter, with leaf edges as sharp as any knife blade.

Many Euphorbia from Africa evolved to fill the same niche as American cacti

The Desert Biome room at the greenhouse, filled with dangerous plants

Despite all the dagger-like thorns and razor-edged leaves, these plants must still be cared for with regular watering, re-potting, pruning, and cleaning. Because the plants are precious, they must not be damaged in the process. But still, the slightest inattention might result in a painful skin puncture or laceration. Working with such a collection requires constant vigilance to avoid injury...and a supply of bandages.

Paddle cactus (Opuntia) grows outside the greenhouse doors, and needs regular weeding

Cacti are the obvious culprits, but there are many other plants unrelated to cacti with vicious needles, spines, and prickles. Cacti evolved in the Americas, but other continents and islands have their own thorny representatives. Africa is noted for its euphorbias, which often grow in forms almost identical to cacti (convergent evolution). Other genera in the collection at the U of M that are capable of drawing blood on the slightest touch include the bromeliads, cycads, agaves, yuccas, and aloes, and many others.

When window sills need cleaning this tippy 5-foot cactus need to be moved...carefully

Dead leaves need to be removed with care from this tree-like cactus (Pereskia bahiensis)

In a moment, this hundred-pound aloe might slice open an arm of the unwary (...me)

Puya alpestris , a bromeliad, and quite dangerous to handle

Adenia spinosa, an African succulent as spiked as any cactus in the Americas. Six-foot branches have a mind of their own.

Bullhorn acacia tree, trades poisonous sap for razor wire barbs (housing angry ants)

Yet, there is beauty among the barbs, the 18th century aristocratic woman, Mary Delany, became a trailblazing artist who literally invented the art of the collage-- or "paper mosaics," as she called them. She used bits of paper to fashion lifelike reproductions of her favorite plants. As and elder woman in her 70s she created more than 1000 botanical collages until her failing vision stopped her. In her piece "Nodding Thistle," she depicted the elegance of a spiky plant, emphasizing its forest of thorns.

Carduus nutans, nodding musk thistle, "paper mosaic" by Mary Delany (British Museum)