Forming the cell walls of stems, leaves, and roots, what compound is the primary structural constituent of plant tissues?

cellulose

Explanation:

Cellulose is plant constituent composed of a huge number of glucose units. It is the main structural component of the primary cell wall of plants. Cellulose is usually in mixture with hemicellulose, lignin and pectin. Because of its structure, cellulose is responsible for the  strenght and rigidity od plant cells.

because of

answer: angiosperms

dicots

angiosperms are highly evolved plants, they produce seeds which are enclosed within in a carple. these are the largest group of plants on earth. they include trees, shrubs, herbs and small flowering plants. angiosperms exhibit a flowering stage in their life cycle. the flower serves the function of reproduction and fruit formation in majority of angiosperms. dicot is the term used to describe flowering plants that have two seed leaves. dicots are plants which develop seeds which split into two parts called cotyledons. each cotyledon contains one embryo.

here, a small purple flower development indicates that the plant belongs to angiosperms and having two embryonic leaves indicates it belongs to dicots.