Plants are composed of specialized groups of cells that work together:
The study of flowering plants (Angiosperms) generally breaks down into three major structural levels: Download ANATOMY FLOWERING PLANTS pdf
The internal structure of Dicot vs. Monocot roots, focusing on the epidermis, cortex, endodermis, and the vascular cylinder (stele). Plants are composed of specialized groups of cells
Mature cells with specific roles, divided into Simple (Parenchyma, Collenchyma, Sclerenchyma) and Complex (Xylem for water and Phloem for food). 2. Anatomy of Vegetative Organs This is usually the "meat" of any PDF on the subject: focusing on the epidermis
The gold standard for a clear, concise introduction to "Anatomy of Flowering Plants."
If you are looking for academic-grade texts, I recommend searching for these specific open-access sources:
The "growth engines" of the plant. Includes Apical meristems (roots/shoots tips for length) and Lateral meristems (vascular cambium for thickness).