Typically, botanical gardens and arboreta must have a full-time scientific staff, an herbarium and library, and a catalogued collection of thousands of plants. Although botanical gardens and arboreta may also have a public viewing area, in which case they may be listed as well under Public Gardens, it is the presence of a viable research faculty using an herbarium or herbaria which distinguishes botanical gardens and arboreta from public gardens. This tends to make botanical gardens and arboreta larger in size and more dedicated to preservation of plant taxa than Public Gardens, however size or reputation are not the determining factors.