Tag Archives: thorns

Plants: Why it Pays to Be Prickly

5 Apr
Didierea madagascariensis (Octopus Tree)

Didierea madagascariensis (Octopus Tree), close-up

While most people would bristle at the thought of being called prickly, a plant would consider it quite the compliment.

For us, prickliness has negative connotations. A prickly disposition means someone is easily irritated, a prickly sensation is one that is itchy and scratchy, and a prickly situation is one to avoid.

But for a plant, prickliness pays. It is a protective adaptation that allows the plant to survive while facing multiple challenges, the main one being herbivores hoping for a nice snack. In my garden, carnivores of the canine variety are the bigger problem; their rampages through the flower beds in pursuit of squirrels have felled less-protected plants. But even they now know not to tear through the rose garden.

In common parlance, the terms “prickles,” “thorns,” and “spines” are often used interchangeably, but botanically speaking, they are different things: prickles come from a plant’s epidermis (the outermost cell layer) and break off quite easily, thorns are modified plant stems, and spines are modified leaves or parts of leaves. Rose “thorns” are actually prickles.

In this post, I’ll focus on spines. Why? Because it still boggles my mind that spines are ….  (modified) leaves.

Didierea madagascariensis                                       Pachypodium lamerei

Aside from being a source of protection, spines serve an important function for xeric plants (xerophytes: plants that have adapted to survive in environments with little water; cacti, aloes, agaves and other succulents are xeric plants). In desert areas, most plants with large, thin, flat leaves wouldn’t last very long; they would lose too much water. So desert plants had to adapt, or die. One of their adaptations was the modification of leaves into spines. Compared to traditional leaves, spines have a very small surface area, which reduces water loss. They reflect sunlight, deflect drying winds, and provide shade to the plant. At night, when it’s cooler, spines collect and drip condensed water vapor.

Knowing all this has expanded my thinking about “prickliness;”  in this case, the pricklier the situation, the better!

Cleistocactus winteri (Golden Rat Tail cactus)


Beyond Flowers

6 Apr

Yesterday, a daffodil finally bloomed in my garden–the very first flower of the season. Because of the cold snaps we have had, the garden is weeks behind schedule.  There are buds aplenty, but with only one lone flower, there isn’t a great deal of interest just yet.

So we went to see what was happening at the US Botanic Garden, where the Conservatory was brimming with tropical plants in bloom, and the outdoor gardens featured an assortment of early-spring flowers. As lovely as they all were, I found myself drawn to other parts of the plants–the peeling, ribbed, spiked, thorny, and veined bits.

They reminded me that flowers aren’t the only things that add excitement to a garden: bark, branches, foliage, and many other parts can be just as captivating. Especially when there are no flowers to be had…. And, admittedly, even when there are.

Iris Rhizomes                                         Leaf of the Quinine Tree

Branch of the Madagascan Ocotillo Tree

Bark of the Quiver Tree