Some plants have glossy green leaves. Some have colorful flowers. Some plants have long, sharp spikes. Amazing to look at and painful to touch, cacti and other prickly plants are always a favorite with young children. This book explores how many plants use thorns or spikes to defend themselves from animals that want to eat them. When it comes to cacti, the spines of these plants are actually long, thin leaves that have adapted to keep the plants from...