Final answer:
Stigmaria is the root system of Lepidodendron, a tree-like plant. Cycads are gymnosperms that resemble palm trees. Horsetails, also known as Equisetum, have hollow stems and were once used as scouring pads.
Step-by-step explanation:
Stigmaria is the underground root system of ancient tree-like plants known as Lepidodendron. They existed during the Carboniferous period and are considered fossils. Stigmaria helped anchor the plants in the ground and facilitated nutrient absorption.
Cycads are a group of gymnosperm plants that thrived during the age of dinosaurs. They have large, compound leaves and bear cones for reproduction. Some cycad species are endangered, and they are often mistaken for palm trees due to their appearance.
Horsetails, also known as Equisetum, are plants with hollow, ribbed stems and whorls of tiny leaves. They can be found in marshes and were once used as scouring pads. They perform photosynthesis in their stems.
Lepidodendron is an extinct tree-like plant that existed during the Carboniferous period. It had a tall trunk covered in leaf scars and spore-bearing structures called strobili. The plant's underground root system is called Stigmaria.