The flora of the region varies greatly at the present time. Land-use has altered the original floral communities, especially in the intensively cultivated area of western Cowley County and in the river valleys.

The sandy Arkansas River floodplain exhibits several stages ranging from sparsely vegetated sandy mounds near the river through stages of Johnson grass, willow, and cottonwood, to an elm-hackberry fringe-forest. The Wellington formation bordering the floodplain supports a prairie flora where not disturbed by cultivation; Gates (1936:15) designates this as a part of the mixed bluestem and short-grass region. Andropogon gerardi Vitman., Andropogon scoparius Michx., Sorghastrum nutans (L.), and Panicum virgatum L. are important grasses in the hilly pasture-lands. Although much of this land is virgin prairie, the tall, lush condition of the grasses described by early writers such as Mooso (1888:304), and by local residents, is not seen today. These residents speak of slough grasses (probably Tripsacum dactyloides L. and Spartina pectinata Link.) that originally formed rank growths. These no doubt helped conserve water and stabilize flow in small headwater creeks. Remnants of some of these sloughs can still be found. The streams in the Flint Hills have fringe-forests of elm, hackberry, walnut, ash, and willow.

Eastward from the Flint Hills these fringe-forests become thicker with a greater admixture of hickories and oaks. The north slopes of hills also become more wooded. However, grassland remains predominant over woodland in western Chautauqua and Elk counties, whereas in the eastern one-half of Chautauqua County and the eastern one-third of Elk County the wooded Chautauqua Hills prevail. This is one of the most extensive wooded upland areas in Kansas. Hale (1955:167) describes this woodland as part of an ecotonal scrub-oak forest bordering the Great Plains south through Texas. He found stand dominants in these wooded areas to be Quercus marilandica Muenchh., Quercus stellata Wang., and Quercus velutina Lam.

Few true aquatic plants were observed in the Arkansas River although mats of duckweed were found in shallow backwater pools at station A-3 (Fig. 2) on December 22, 1956. In the Walnut River Najas guadalupensis Spreng. was common at station W-2. Stones were usually covered with algae in both the Arkansas and Walnut rivers. A red bloom, possibly attributable to Euglena rubra (Johnson), was observed on a tributary of the Walnut River on July 9, 1956, at station W-4.

Green algae were abundant at all stations in the Caney, Elk, and Grouse systems during May and June, 1956, and reappeared late in September. Chara sp. was common in these streams in April and May.

The most characteristic rooted aquatic of streams in the Flint Hills was Justicia americana L. At station G-7 on Grouse Creek and Station C-8 on Big Caney River (Fig. 3), Nelumbo lutea (Willd.) was found. Myriophyllum heterophyllum Michx. formed dense floating mats at a number of stations. Other aquatic plants observed in the Caney, Elk, and Grouse systems included Potamogeton gramineus L., Potamogeton nodosus Poir., Potamogeton foliosus Raf., Sagittaria latifolia Willd., Typha latifolia L., and Jussiaea diffusa Forsk.