This may seem like a question for poets, but botanists know why roses have thorns.
First of all, to set the record straight, roses do not have thorns. They have prickles. Thorns are modified leaf stems or parts of leaves, while prickles grow from the epidermis or cortex.
Rose prickles serve to keep away predators. Rose plants are tasty, according to deer. The prickles, sometimes brightly colored, say “keep away!” This message is also directed at you, Mr. and Ms. Florist. Roses don’t want their flowers stolen.
But most rose prickles curve down to serve another, more insidious purpose. When roses grow, they clamber over other plants. The prickles serve as hooks to help anchor rose branches into their unfortunate neighbors. But as the roses grow, they can monopolize the sunshine, and the plants they grow over will starve and die. Roses don’t care.
Thus we can conclude that if someone gives you a rose, this is hardly an act of love. The flower didn’t want to be harvested and handed over to you, and roses are nasty plants anyway.
Poets, take note. Rather than roses, praise the love apple. When it turns a beautiful color and becomes aromatic, it’s inviting you to take it and share it as a true symbol of esteem, nurture, and even passion. Nothing says love like a tomato.

This is my new favorite plant, a Rhipsalis creuscula or
The Locus Science Fiction Foundation 

A host of The Nerd Cantina podcast interviewed me at the Chicago Comic and Entertainment Expo last month, and you can hear it in this week’s show, 
The members of Spectology: The Science Fiction Book Club Podcast may have thought harder about my book than I did. In the episode
Semiosis has been published in Japan by Hayakawa Publishing, Inc., translated by Maasa Mizukoshi.