Final answer:
The adjective clause in the sentence provided is 'who wears flowers in her hair', modifying the noun 'teacher'. It provides additional information about which Spanish teacher is being discussed and starts with the relative pronoun 'who'.
Step-by-step explanation:
The adjective clause in the sentence 'My Spanish teacher who wears flowers in her hair is very pretty.' is 'who wears flowers in her hair'. This clause describes the noun 'teacher', indicating which specific teacher is being talked about. An adjective clause functions as an adjective in the sentence and often begins with a relative pronoun such as 'who', 'which', 'that', or 'whom'. The main subject of this sentence is 'My Spanish teacher', while the adjective clause qualifies and gives additional information about the teacher.
Essentially, adjective clauses act similarly to adjectives in that they modify nouns. In contrast to simple adjectives, which are usually a single word, adjective clauses are groups of words that contain a subject and a verb. The importance of recognizing these clauses lies in understanding the specific details they provide about a noun, enhancing the description provided.