Most students can recognize that plants come in many different heights, widths, and overall forms. Below is a listing of some of general plant forms that exist in the world.
Trees: Plants that are large or tall and possess wood are considered trees by botanists. Trees may be shade-tolerant or prefer full sun. These are usually flowering dicots or cone-bearing evergreens. True trees (vs. tree-like plants) are the height record breakers, such as the redwoods of California (Sequoia sempervirens), which can reach almost 400 feet tall.
Tree-like plants: Many monocots and some ferns reach tree size and stature, such as palms, bananas, bamboo and tree ferns. Botanists avoid calling these plants “trees”, because they do not contain wood. Woody trees increase in girth over time, but these plants remain the same width from top to bottom. Therefore, they use roots, leaves and other features to support their height.
Shrubs or bushes: Similar to trees, shrubs are plants that are small and woody. Unlike most trees, shrubs produce many smaller stems than one large trunk. Shrubs may grow in full sun as a successional species, or as a shade-tolerant plant in a forest. Shrubs are usually dicots.
Vines and lianas: Unlike the other plants mentioned, vines and lianas obtain light by growing up on top of other trees or structures. Vines are usually herbaceous, but lianas are woody. Young vines are adapted to low-light, but mature plants are usually in full-light of the tree canopy. This form exists in dicots, monocots, gymnosperms and even ferns!
Herbaceous plants or herbs: Plants that are soft and green are called herbaceous. Herb is short for herbaceous, but we usually think of fragrant plants used for cooking. These plants are usually small or smaller than trees. Ferns, grasses, tulips, and most vegetable crops are examples of herbaceous plants.