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33 Vascular Plants Because of the great diversity of natural communities and vegetation types found within the borders of Indiana, there is a corresponding diversity of vascular plant species. Floras published in 1881, 1900, and 1940 recorded native species in the state totaling 1,194, 1,400, and 1,838, respectively (Deam 1940). Charles C. Deam, Indiana’s preeminent botanist of the twentieth century, was exceptionally thorough in his efforts to document the state’s flora. He believed that the number of native species for Indiana would never surpass 1,900, yet the total now approaches 2,000 (K. Yatskievych , unpublished data). This has been the result of intensive and extensive fieldwork, so that the current list of all vascular plants in Indiana (Table P-1) now totals more than 2,900 species, subspecies, and varieties . This total includes many introduced, alien, and adventive species that now reside in Indiana and are either reproducing or have sustaining populations in the state. Many, if not most, of these species introductions have occurred since Deam’s exhaustive survey (Deam 1940). Perhaps another factor contributing to the increase in species number is the natural range expansions of certain species that entered the state in the late twentieth century, particularly those with wind-dispersed seeds. These additions, offset by the probable extirpations of species before they were documented, make it safe to say that the number of native vascular plant species known to occur in Indiana in the past two centuries has been approximated at 2,000. Of this number, 55 species are thought to be extirpated from Indiana (Indiana Natural Heritage Data Center 2005). The number (and geographic area) of non-native plant species has clearly increased in the state since 1800, in terms of both species and individuals. The flora of 1881 included 140 non-native species; 177 were listed in 1900, and 302 in 1940. That figure jumped to nearly 800 in 2005. The latter is an indication of increasing globalization in trade and travel, which results in the purposeful as well as inadvertent introductions of species. 1800. With the vast numbers of natural communities and relative lack of invasive non-native species, the native flora of Indiana was at its most diverse and expansive at this time. The majority of the nearly 800 non-native species known in 2000 were not present, and the now-extirpated species would have occurred, some perhaps in large numbers, at least locally (e.g., western beard tongue and prairie white-fringed orchid ). Species requiring high light intensities, such as those in prairies, barrens, fens, marshes, and open woodland, would have existed in great numbers due to the high frequency of fire on the landscape. Fire would have suppressed woody vegetation, thus reducing shade. In the graminoid communities, a myriad of grasses, sedges, and forbs would have dominated, including big bluestem, little bluestem, Indian grass, switchgrass, prairie cordgrass, northern dropseed, river bulrush, great bulrush, common tussock sedge, marsh blazing-star, downy sunflower, prairie dock, black-eyed Susan, and rattlesnake master. In the woodland communities, some of the species most likely benefiting from canopy thinning and litter consumption by fire would have been woodland sunflower, forked panic grass, violet bush clover, crownbeard, soft agrimony, woodland brome, buffalo clover, nodding fescue, elm-leaved goldenrod, and early oak sedge. Running buffalo clover, a federaland state-listed endangered species, was apparently widespread in southern Indiana in areas of moist alkaline soils. Eastern red cedar is sensitive to fire and was greatly restricted to sites that did not readily burn (e.g., rocky, low-fuel sites). Once fire was controlled, it spread across pasture land and abandoned cropland. Black locust was primarily found in the southeastern part of the state until it was spread through planting for fence posts and as a home-site ornamental and honey source. Land clearing, beginning in the early part of the nineteenth century, began the reduction in species and numbers of plants, especially those of prairie and wetland habitats. Some species were impacted significantly . It is clear that bald cypress, American larch (eastern), and arbor vitae (northern white cedar) probably disappeared from many areas before their occurrence could be documented. 1900. By 1900, most of Indiana had been cleared of natural communities. Huge tracts had been converted for agricultural pursuits, either for row crops or pasture. Consequently, many species declined. Sites not as suitable for farming were spared somewhat, but these were commonly disturbed by livestock. A few plant species are thought to have...

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