the stipe diminish to hairs as one moves towards the tip of the leaf. The overall shape of the blade ranges from oblong (tapering at the ends but about the same width throughout) to lanceolate (slightly wider a short distance above the base, tapering to a point at the apex). It is squared off at the base and tapers at the tip. The blade ranges from long, rarely to , and in width, and may be thin or somewhat thick. The blade is cut into 5 to 15 pairs of pinnae (possibly as low as 3 or as high as 20 in unusual specimens), which are themselves deeply lobed or further subdivided into pinnules. The lower pinnae are stalked, while the upper pinnae are not. They are variable in shape, tending to have a squared-off or very broadly curved base, and are typically widest at or near the base. The acroscopic lobe or pinnule nearest the rachis (located on the apical side of each pinna) tends to be enlarged, and the pinnae are toothed. They vary from in length and at the middle of the frond. Each pinna on a fertile frond has three or more pairs of sori. These are long, and rusty or dark brown in color. They are located between the margin and the midvein of the pinnae. The sori are covered by opaque indusia with untoothed edges. The indusia from white to light tan in color and have a membraneous texture. Each sporangium holds 64 spores. The species has a chromosome number of 144 in the sporophyte, indicating an allotetraploid origin. It sporulates from June to December. Variants of A. bradleyi have been reported. Specimens found growing in a very shaded environment, which lacked color in the rachis and were simply pinnate, have been mistaken for green spleenwort (A. viride). But even under such conditions, A. bradleyi has a more leathery leaf texture than A. viride, and their ranges do not overlap. In 1923, Edgar T. Wherry described what he believed to be a new species of fern, Stotler's spleenwort (A. stotleri) (after T.C. Stotler, its discoverer). Wherry believed it to be the hybrid of lobed spleenwort (A. pinnatifidum) and A. platyneuron. However, it was later shown to be simply a form of A. bradleyi with rounded, rather than sharp, teeth. A dwarfed form of A. bradleyi, with fronds about long, was discovered in Illinois by