What is a herbarium, and what is it good for?

Herbarium specimen sheet for (Accession Number 191229). Collected on June 4, 1964.

A herbarium is a facility housing a collection of dried, pressed plant specimens. These specimens are useful for many aspects of plant study. Examples are:

references for identification
location and distribution of species
producing regional field guides and floras
habitat and ecology
phenology (time of flowering, fruiting, etc.)
morphological variation
determination of rarity
documenting spread of invasive species
DNA sampling for systematic research
The specimen shown here is an Indian paintbrush, Castilleja chromosa, common in western Colorado. The specimen retains most of the characteristics of the live plant including such diagnostic features as the hairs visible in the close-up (inset) of the specimen. The label on the bottom right of the herbarium sheet contains the vital information regarding location, habitat, and date of collection.
If kept dry, stored away from light and insects, and handled carefully, specimens can last for hundreds of years, only gradually fading in color and becoming more brittle. A herbarium is a botanical library containing a wealth of knowledge about thousands of plant species.

If you are interested in learning more about the specimens housed at the Herbarium, the Specimen Database of Colorado Vascular Plants is available online. This fully searchable database contains complete label information for over 70,000 specimens of Colorado vasculars.