Learning Objectives Tissue Organization in Leaves All three tissue types are represented in leaves. The epidermis represents the dermal tissue, the mesophyll that fills the leaf is ground tissue, and the vascular bundles that form the leaf veins represent vascular…
Learning Objectives Each leaf typically has a flat, wide portion called the blade (lamina), which is also the widest part of the leaf (Figure ). Some leaves are attached to the plant stem by a stalklike petiole and are called petiolate leaves (Figure ). Although petioles…
The stem of a plant bears leaves, flowers, and fruits. Stems are characterized by the presence of nodes (the points of attachment for leaves or branches) and internodes (regions between nodes). All three tissue systems can be found in stems. In the primary stem,…
Learning Objective Define and provide examples of the major stem and shoot modifications. Stems (or entire shoots) of some species deviate in structure and function from a typical stem. These are called stem modifications (shoot modifications). While leaves are part of the shoot,…
Learning Objectives Primary growth occurs as a stem increases in length as a result of cell division in the shoot apical meristem. Secondary growth is characterized by an increase in thickness or girth of the plant, and is caused by cell division secondary…
Learning Objectives The primary stem refers to the herbaceous (non-woody) stem, which has not undergone secondary growth (the growth that produces bark and wood). Some species (all monocots and some eudicots) remain herbaceous for their entire lives, maintaining the primary…
Learning Objective Identify the main external structures of the shoot system, including the nodes, internodes, leaves, axillary buds, and axillary shoots. Plant stems, whether above or below ground, are characterized by the presence of nodes and internodes (Figure ). Nodes are points of…
Roots help to anchor a plant, absorb water and minerals, and serve as storage sites for food. Taproots and fibrous roots are the two main types of root systems. In a taproot system, a main root grows vertically downward with a few lateral roots. Fibrous…
Learning Objective Describe the types of modified roots and their functions. Root structures may be modified for specific purposes. For example, some roots are bulbous and store starch. Tap roots in plants such as carrots, turnips, and beets, are examples…
Learning Objectives Root Anatomy Root growth begins with seed germination. When the plant embryo emerges from the seed, the radicle of the embryo begins to grow downward and forms the root system. As the root system grows, various structures begin to appear.…