I never assume I know it all or even half of “it”, whatever that is. After listening to Gabriella Plants Podcast, Episode 31, that I learned that “Every rose has its prickle”. Poison needs to change their 1988 hit single lyrics. Roses don’t have thorns, but prickles. Crazy?!! What IS a prickle and what is a thorn, or a spine? Are they different? Yes, they are.
Did you know a rose thorn is a prickle? I didn’t and I’ll never look at a rose the same again. I wondered how this related to houseplants, of course, and I found a plant this weekend when visiting a local conservatory. The silk floss tree or Ceiba speciosa also has prickles. What are prickles? Prickles come from the epidermis of the plant or the “skin” of the plant. They don’t contain any vascular tissue such as xylem or phloem, so they are easily removed. When your bouquet of roses arrives at the door, the prickles have hopefully been removed because they can be painful, like thorns.
Many hardy plants (in Michigan) have thorns, such as hawthorn trees, old-fashioned quince, and pyracantha or fire-thorn. I have a couple of quinces, but they are newer cultivars and so have no thorns. A plant I do have and you may also, is a Meyer lemon tree. It has some wicked thorns that emerge from every leaf axil. You may have found out the hard way, as I did. True thorns are modified branches. Because they are branches, they do contain vascular tissue and are harder to remove from the plant.
So we come to spines. These are more familiar to most as they are on cacti and on some succulents such as euphorbias. The ones on euphorbia are called stipular spines and you can read more about those here. The familiar euphorbia to most would be the crown of thorns or Euphorbia milii, which should be called the crown of spines. Crazy, right? Roses have prickles, and crown of thorns have spines, botanically speaking. Who knew? Spines are modified leaves and so though the crown of thorns (spines) has leaves, most plants in the cacti family do not. (They do, they are just modified to become spines.) Should we call it a crown of spines from now on? Spines are also tied into the vascular system of the plant and therefore are not easy to remove.
Below are a couple of cacti with obvious spines. Yikes!
Why do Plants Have These?
The most obvious reason plants have these appendages are to keep herbivores away. Few animals want to bite into a plant full of sharp spines/prickles/thorns. Yet, deer are fine eating roses. In my experience, deer will eat almost anything! Sometimes the spines are so packed together on a cactus, it can also keep insects from invading. These will not keep the mealybugs from attacking and the spines then make it almost impossible for you to get them out. In the case of some of these plants that grow in extremely hot and sunny spots, these spines also act as a sunscreen. So they are useful to the plant, just painful to we caretakers of them.
Did you learn something new today? Did it blow your mind? It sure did mine when I found out that roses have prickles, not spines. And crown of thorns should be a crown of spines. Crazy!
Have a great week, plant friends!