A collection of pressed and dried plant specimens, and a description of when, where, and by whom they were collected, arranged in a systematic manner, and serving as a permanent physical record of the occurrence of an individual plant at a specific place and time. Herbaria may contain specimens from the full range of organisms that have classically been considered plants: fungi, lichens, algae, bryophytes, ferns and their allies, gymnosperms, and angiosperms. Many herbaria also accumulate and manage special collections such as liquid-preserved parts for anatomical studies, wood, seeds, or specially preserved material suitable for extraction of deoxyribonucleic acid (DNA) or other chemical constituents. Many groups of plants, especially those with succulent or fleshy parts, are not suitable for preservation as dry, flat specimens because they lose many of their important features in the drying process. Consequently, these plants are often preserved in liquid. Specimens are used in taxonomic and ecological research, such as morphological studies, and for comparative identification and verification of unknown specimens. Plant geography Plant taxonomy