Blackstem Spleenwort
Asplenium resiliens - Kunze
Aspleniaceae (Spleenwort) Family


Blackstem Spleenwort is a small fern with pinnate fronds (leaflets placed opposite each other), growing in erect tufts, with a shiny black stipe and rachis (stem and leaf axis), having sterile and fertile fronds of similar appearance. The roots are thin and wiry, but do not spread to form new plants. The rhizome is about .08 inch in diameter, and has variously been described as sometimes branching or may be unbranched. The plant bears stiff lance-shaped scales, which are blackish in color and in an obscurely lattice-like pattern, or may be entirely black.

The leaves are erect and varying in size from 1.2 to 18 inches long and about 1.5 inch wide. The stipe (stem below the leaf blade) is straight and stiff and a glossy black to purplish-black in color. It may be smooth or bear scattered blackish-brown, threadlike appressed scales. The stipe usually measures about 1 inch long and about 1/4 the length of the blade. It is round in cross-section and will have slightly flattened wings on either side. The leaf blade is linear in shape, sometimes slightly wider below the tip or just above the base and measures about 14 inches long and about 0.8 inch wide, abruptly converging to a lobed, pointed tip and gradually tapers at its base. The leaf tissue is often bluish-green and thick in texture. The stem, like the stipe, is rounded, blackish and shiny. The wings of the stipe extend up the stem. The blade is cut into leaflets throughout its length, each leaflet is sessile (stalkless), but may have minuite stalks that are rectangular in shape, tapering slightly toward the tip.

The leaf veins do not join one another and are difficult to see; fertile veins are once-forking and do not terminate in the usual swellings as would normally be expected. The spores appear on both sides of the midrib and are crowded at the edges and often merge or fuse together as they age.

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