Cacti and Cactuses, A Dark History of Houseplants, and Treetown, Sierra Leone
Updated: Mar 5, 2021
"We abuse land because we regard it as a commodity belonging to us. When we see land as a community to which we belong, we may begin to use it with love and respect."
"We don’t inherit the earth from our ancestors, we borrow it from our children."
- Native American proverb
The Incredible Range of Cacti
My partner and I are currently crossing the country in an RV, a type of mobile quarantine, in order to visit our east coast family this holiday. The drive from Venice, California took us through some northern states I’d never visited before. We spent a night at Palisades State Park near Garretson, South Dakota and hiked along the rocky edges of the park’s central gulch. The air was a chilly 37° F, but not the coldest these parts see - for three straight months each year, this park doesn’t see average temperatures above freezing. So I was confused to see small needled plants poking up from between the pink Sioux Quartzite crevices. I initially assumed someone spilled a houseplant, as the cactus paddles were wrinkled and browning. But these penny-sized paddles were everywhere, much larger of a spill radius than would make sense. And they were all firmly rooted. Taking some subpar iPhone photos, I wondered how a desert plant came to grow in a place with an average yearly rainfall similar to Oregon and an average annual temperature only 12 degrees above freezing.
The word cactus conjures up images of quintessential saguaros or squat golden barrels, some thick fleshy stems covered in thin sharp spines poking out of the desert sand. Many of us don’t associate cacti with northern climates, because the majority of the species grow in hot, dry regions. In North America, cacti are most prevalent in Mexico and many parts of the Southwestern United States.
But cacti also grow in places very different and very far from these deserts - on mountains, in rainforests, and (apparently) in South Dakota gulches. There are even some cacti growing near Antarctica and the Arctic Circle.
One quick note: Cacti vs Cactuses.
According to grammerist.com: “Cacti is the Latin plural of cactus, and some writers use it in English. Cactuses is the English plural. Dictionaries list both, and neither is right or wrong. Also, like many names of plants, the uninflected cactus is sometimes treated as plural.” So go ahead and say whatever feels good. For me, the less syllables the better. Back to the cacti...
Even though they are found growing on almost every continent today, all of the 2,000 species of cacti are native to the Americas (except for one). Like most living organisms, cacti species can vary greatly from one to the next. Some cacti resemble spiky beach balls, some look like brains, and others swing in the breeze like green braids. Even within species, cacti can vary in appearances; certain individuals may look very different from their parent plant and/or their neighbors.
The appearance of any plant has much to do with its methods of survival. You may remember your high school biology teacher repeating the phrase “form and function”. This idea refers to the direct relationship between the structure of a thing and the way it operates. In the case of cacti, the form or structure of the whole, as well as the form or structure of each of its parts, has a distinct reason for being just so. In other words, to survive in various environments, different species of cacti have evolved different shapes, spines, flowers, and hues.
Cacti in the Cold
The little cacti I observed in South Dakota is known as the Brittle Prickly Pear Cactus (Opuntia fragilis), and it turns out that, despite it's feeble name, this is the hardiest cacti of the Northern Americas. They grow in almost every state west of the Mississippi and can be found growing at 56º North latitude in Alberta, Canada -- this is less than 10º from the Arctic circle!
Opuntia fragilis share many features with the cacti of the desert. Cactus plant shapes usually maximize internal volume and limit external surface area. Their skin is thick and waxy to reduce loss of moisture and to reflect heat. The thin, spiky thorns of all cacti are actually modified leaf tissue; cacti do not need the big flat leaves of tropical plants because they are not fighting for sunlight. Leaf tissue is converted into spiky thorns to serve as a protection mechanism against predators and as a guide for rainwater and fog down to the base of the plant. Photosynthesis occurs in the green tissue of the stems.
There is one lethal environmental factor northern grown Brittle Prickly Pears deal with that it's many desert brethren do not -- subzero weather. O. fragilis can tolerate some really cold temperatures, like negative 40° F kind of cold. One function of their smaller form is to keep them close to the ground and therefore easily covered by protective snowfall. They huddle under a blanket of snow warmer than the freezing air above. O. fragilis also enacts a water-losing process which reduces the hazard of frost injury. This process resembles wilting and ends with the plant looking shriveled and brown. But with the return of warmer weather, the plant slowly takes up water, greens up, and fills back out.
Cacti in the Canopy
Halfway around the world and much closer to the equator, another cactus thrives in near opposite conditions. Rhipsalis baccifera, or the mistletoe cactus, is the only species in the cactus family that naturally occurs in the old world, and scientists still aren’t quite sure why it lives so far from its kin. Originally documented growing in the jungles of Africa and India, today the species grows wild all over the tropical world, in areas with as much as 160 inches of average rainfall. These epiphytic plants hang from tree branches in long slender stems, like tree spaghetti, getting their nutrients and water from the very air around them.
Cacti in the Mountains
The Andes Mountain range is home to some truly awesome cacti. In Chile, some species of Copiapoa, growing at 1600 feet above sea level are estimated to be over 400 years old. Copiapoa is one of the oldest cacti species growing in the Andes. The plant is well adapted to life in dry, rocky areas of the Atacama Desert that may go years without any rainfall. Some areas of this desert region are estimated to have gone without rain for over 400 years. Luckily, the Copiapoa has the sea. Cold air from the Pacific Ocean moves over the hot land producing abundant, almost daily, fog.
The Argentinian Andes harbor the Trichocereus (or torch cactus), a psychoactive cacti well known for their ceremonial use by indigenous peoples. It is thought that the psychoactive compounds are produced by the plant in order to deter herbivores, but the jury is still out, and it's quite the opposite of a deterrent for many humans.
And in Peru, growing three miles above sea level, a cacti community thrives. The Punotia lagopus, Austrocylindropuntia floccosa, and Lobivia maximiliana have been observed, by cacti researchers and enthusiasts, growing at altitudes over 4600m. Each of these species grows a thick cover of spines, almost hair-like, to protect from the sun’s intense rays at these high altitudes. Surprisingly, you can buy a Lobivia maximiliana for $9.00 on Etsy.
Cacti in the Middle of the Ocean
There’s one frontier you don’t expect to find much life, and that’s a lava field in the middle of the ocean. But life thrives in the Galapagos, and with much thanks to one cactus species. The Lava Cactus (Brachycereus Nesioticus) turns inhospitable volcano debris into an ecosystem.
Each island in the Galapagos Archipelago formed from numerous volcanic eruptions, which created vast barren lava fields. These sloping volcanic islands are some of the most inhospitable environments imaginable. But the Lava Cactus has adapted to this harsh landscape and through its own decay, creates the soil necessary for other plants to establish. After the secondary plants take root, the animals can follow.
From the frigid high latitudes of northern Canada, to the humid rainforests of Southern Africa, in the driest mountain range of the world, and on the lifeless lava fields of the Pacific Ocean, the plant family Cactaceae thrives where most other life cannot. The casual awesomeness of cacti.
Some interesting plant things to check out...
1. The Dark History of Houseplants. Every Little Thing is a quirky, pun-heavy podcast trying to answer all the odd questions people have about life and the things around us. In last week’s episode, they weed through the numerous houseplant heydays, from the beginning of potted plants and the dark history of orchid collecting to the current “cuttings” craze.
2. Politicians Planting Trees. There is a fresh mayor of Freetown, Sierra Leone who is rallying her city to plant one million trees in the next two years:
3. The black market of cacti sales. There are microchips in 1,000 cacti in Saguaro National Park because hipsters and horticulturalists all over the world are demanding more cacti for home display. Good read by the Pacific Standard on the larger issues here.