Diversity of Vascular Plants and Intensity of Plant Collecting in Nebraska

A computerized database of Nebraska\u27s flora has been made from specimens in 20 herbaria. Almost 1,900 species of native and escaped-alien vascular plants have been collected in the state since the mid-1800s. The flora of some counties is very well known but that of many counties, especially southwestern and Sandhills counties, is poorly collected. More than 800 species (nearly 100% of the species that are likely to occur) have been collected from each of Cherry, Douglas, Lancaster, and Richardson counties, but fewer than 150 species are known from Fillmore and McPherson counties, less than 25% of the potential number species to be found there. Collectively, the state\u27s floristic list is approaching completeness, although that condition has yet to be reached for many counties individually. Most newly found species are nonnatives and are often weedy and of temporary occurrence at a given site; few new state records can be made of native species but many such records are possible from counties. The Asteraceae and Poaceae have the most species in many habitats, and some rich habitats contain as many as two-thirds of Nebraska\u27s plant families. No native species is known to be extirpated from the state, but many natives are reduced to a few isolated populations