The UCR herbarium housed some 406 specimens that are types of various sorts. Thirty-two of these are holotypes, some of which are listed further down this page.

A type in general is the specimen (or a group of specimens) with which the species has been defined. The botanical type is not unlike the standards for weights and measures that are stored with high security and care by national governments that serve as the definition of the units of length and weight used in that country or the world. If the specimen matches the characteristics of the type, then the scientific name of the type can be applied to the specimen. A holotype (hol[o]-, e.g., whole, complete) is the single specimen referenced in the formal published definition of the species as the holotype. There are other types of types: isotype (135 at UCR), paratype (218 at UCR), topotype (8 at UCR) and cotype (2 at UCR). There are some 11 specimens without a definite specification as to what kind of type they are. There are more types of types, but these (e.g., neotype, syntype, lectotype, paralectotype, hapantotype) are not found in the collection at UCR.

An isotype is a duplicate of the holotype. Often when a specimen is taken from a living plant, there is enough material to fill more than one specimen sheet. These additional sheets are called duplicates and generally are distributed to other herbaria in an exchange relationship with the original herbarium. A paratype is an additional specimen listed along with the holotype in the formal published description of the specimen. A topotype is a specimen collected in the locality where the holotype (and paratypes) was found. A cotype is a specimen collected from the same plant (or organism) from which the holotype was collected. About a fourth of the types have images associated with them. A brief guide to its use is provided after the following lists of holotypes.

The search page is the opening into the database. The search for the text fields requires correct spelling, but not necessary completeness in case of terms consisting of more than one word. For example, "New" in the state search field will get types collected in "New Mexico." If the collector's name includes the person's personal name, the use of the collector's personal name in the collector search field will get you all the collectors whose names include that personal name. Some collectors's names only include the initials of their personal names. In those cases, the personal name in the collector search field will not get you those collectors' specimens.

The year search is exact as is the year range. Note that if you search by year, you can use either the year search or the year range search but not both.

Use of more than one search field is the equivalent of "AND's": the found have to satisfy all the terms.

You can specify the number of records to show per page of the search results from 4 to 12 by setting the last field next to the "Search" button.

The search results will show a small version of an image if there is one associated with the particular type. Clicking on the image will bring up a page specific to that specimen with a larger version of the image. There will be a link to an even larger image of this specific specimen page if one is available. That very large image will range in size from 100 to 200 megabytes. It will take some time for the image to load. They are interlaced. The image will gain in resolution until it is fully loaded.

In the primary result pages, you can sort the results by one of various fields, e.g., collector, accession number, etc. by clicking on the triangles on either side of the field names in the green top "heading."