Answer. Some cacti even have hooked spines! Top Answer. Although a few kinds of cactus are spineless, the stems of the most are covered with an array of sharp spines. Perhaps the first thing you think of is the spines. They may be straight or curved, flat or round, hair-like, bristle-like, needle-like, or awl-like. Why is sun protection needed for the surface of cacti? How to remove cactus spines (including ones stuck in your throat) Experts weigh in on a prickly predicament. To know if your spineless “cactus” is really a cactus at all, check for areoles, which are the spots on the stem where spines, hairs, or flowers would grow. Now you can be … Spines also offer shade from the sun’s strongest rays. Mimi. Why does a cactus have spines?« Back to Questions List. The saguaro cactus is a very unusual looking tree of the desert. A surprising function of cacti spines is to provide shade for the cactus itself. A cactus makes food in the thin, green outer layer of its stem rather than its leaves. If it seems preposterous that such thin objects could offer much shade, look at again at how dense some cactus spines can be. 1 decade ago. Why does a cactus have spines on its stem? At the same time they keep off sunlight, spines can also be keeping the stems cooler and reducing loss of precious moisture to evaporation. Wiki User March 23, 2011 10:45AM. 1 decade ago . May 4, 2018. The spines also protect the cacti from animals that might eat them. It has been the subject of many photographs, and commonly conjures up thoughts of the old west and the beauty of the Southwest desert. Answer Save. The word cactus makes us think immediately of spines. If you have ever been unfortunate enough to have been pricked by a cactus, you’ll likely never forget that most of them have needles. Shelchav Cactus spines are actually modified leaves. These minimise the surface area and so reduce water loss by transpiration. Wiki User October 27, 2009 11:23PM. 1.They are present in hot deserts which are scarce in water so in order to reduce the loss of water by Transpiration from the surface of the leaves, its leaves are reduced to spines.This is a type of adaptation of the plant. Why do cactus plants have thorns? More Environment. Instead, roses have prickles, which are a part of the skin of the plant. The two organs have little in common other than developing from leaf primordia. Finally, some cacti have hair-like spines called glochids. Favorite Answer. Although a few kinds of cactus are spineless, the stems of the most are covered with an array of sharp spines. Along with each saguaro cactus picture, we've included a saguaro fact. Best Answers First, let's look at the spines of cactus for what they really are - the main part of cactus often functions as a modifed stem and its spines are the leaves. Cactus spines grow from specialized regions, called areoles or spine cushions. Answer Save. Shelchav Cactus spines are actually modified leaves. Why does a cactus have spines on its stem? Wiki User October 27, 2009 11:23PM. Why does cactus have spines? Relevance. Cactus spines grow from specialized regions, called areoles or spine cushions. The word cactus makes us think immediately of spines. Mimi. Relevance. These are a hallmark of all cactus species, and are a highly modified branch structure. In plant morphology, thorns, spines, and prickles, and in general spinose structures (sometimes called spinose teeth or spinose apical processes), are hard, rigid extensions or modifications of leaves, roots, stems or buds with sharp, stiff ends, and generally serve the same function: physically deterring animals from eating the plant material. Cactus spines come in a variety of forms. By Kate Baggaley. Cacti don’t lose water from these spines as they are metabolically inactive, but they allow water vapor from the air to condense onto the spines and run down onto the surface of the plant and into the soil, to be absorbed by the roots. This helps keep the cactus temperature relatively low. Top Answer. Spines also offer shade from the sun’s strongest rays. But when you consider that each spine provides a small amount of shade and then multiply that by a 1,000 or more per cactus – it makes it easier to believe that the spines help to protect the surface of cacti.