Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Problem:Passage: Fibrous root systems have many small branching roots, called fibrous roots , but no large primary root. The huge number of threadlike roots increases the surface area for absorption of water and minerals, but fibrous roots anchor the plant less securely. Answer: fibrous roots
Solution:
Fibrous root systems have many small branching roots called what?