An 
herbarium is a 
collection of
          dried, preserved and/or pressed plants, leaves, flowers or fruit, seeds,
          wood sections, pollen and nowadays frozen DNA extractions. Every specimen
          is classified and labeled with full data as scientific name, location,
          date, habitat and description. 
Herbaria (plural
          latin of herbarium) are very important to the study
          of the flora of the world, around 300 million specimens.