The entire Areawide pest management research unit's (APMRU) pollen reference collection was started in 1993. Within the collection are of five types of pollen reference material: permanent glass slides, light micrographs, scanning electron micrographs, pollen vouchers, and field/ herbaria collected polleniferous material. The entire collection consists of about 7500 worldwide taxa. Because of the importance of a good reference collection, it is constantly being upgraded and new taxa are added yearly. The pollen reference collection is actually composed of several components, some of which are on loan. The Stanley D. and Gretchen D. Jones, Meredith Hoag Lieux Collection, and David and Susan Jarzen Pollen Collections are on loan.