Botanists identify plants according to key characteristics such as the area in which the plant is growing, the shape of the plant's leaves, the type of bark or lack of bark and the presence or lack of fruit and flowers. Plants are generally divided into six major groups: woodland, aquatic, grass-like, orchids, ferns and flowering non-woodland plants.
Woodland plants consist of trees, shrubs, non-shrubs and lianas. Woodland plants have thickened outer tissue of the stems and most have bark, as well as buds in the dormant season. Aquatic plants are characterized by submerged or floating leaves that have adapted to withstand flooding. Grass-like plants consist of grasses, sedges and other plants with long narrow leaves. They have leaves with a narrow blade or tubular sheath, or small flowers without obvious sepals and petals.
Orchids and related plants, such as lilies, irises, aroids and monocots, are characterized by seedlings with a single embryo leaf, flower parts in multiples of three and parallel veined leaves. Ferns and related plants, including horsetails, quillworts and lycopods, reproduce by spores. The spores often are grouped in specialized structures. Flowering non-woodland plants do not have parallel veined leaves but do have flower parts in groups of four or five.