The Olmsted Parks of Louisville: A Botanical Field Guide

Plant Descriptions: Ferns and Fern Allies

Ferns and Fern Allies 33 shorter, arched, lighter green; both with 15 to 22 pairs of leaflets. Sporangia: In linear sori in 2 rows on underside of leaflets. Distribution: Moist to dry woods, rocky ledges. Uncommon. In Kentucky: AP, IP, ME. This fern is found in southern Africa and in North America and is unique in that no other North American fern has such a distribution. In Kentucky, ebony spleenwort is one of the most widespread in the state and highly adaptable. It grows in a variety of habitats, from rich shaded woods to dry rocky masonry in urban sites. In old fields, it is often associated with Japanese honeysuckle and Eastern red-cedar. The common name is misleading, as the smooth, dark stem is brown, not ebony black. Ebony spleenwort Spleenwort Family Asplenium platyneuron (L.) BSP Aspleniaceae Key features: Fern from thick rhizomes; stems wiry, brittle, reddish brown; leaves with numerous paired leaflets. Origin: Native. Life form: Perennial fern. Stems: Erect, unbranched, smooth, brittle for fertile blades, shorter and spreading for sterile fronds. Leaves: Fertile ones dark green, erect, narrow, tapering to top and bottom, to 20 inches tall; sterile ones numerous, Cher, Sen, Iroq, Shaw 34 Ferns and Fern Allies Sporangia: In linear sori irregularly scattered along veins on underside of blade. Distribution: Moist, mossy, shady limestone ledges. Rare. In Kentucky: AP, IP, (ME-rare). This unique fern is called walking fern because the blade with a long, pointed tip can sprout a new plant when it touches the ground and takes root. The old, slightly upright, arching fronds often are surrounded by many new young plants that grow flat to the ground. The species name—rhizo is Latin for “root” and phylum Latin for “leaves”— refers to the way the plant spreads. Walking fern Spleenwort Family Asplenium rhizophyllum L. Aspleniaceae Key features: Fern from scaly rhizome; stems flattened, in star-shaped tufts; blades triangular, tapering into a long, thin tip that roots upon soil contact. Origin: Native. Life form: Perennial fern. Stems: Dark reddish brown at base, green and smooth above. Leaves: Of 2 types: fertile ones to 15 inches long, often larger than the sterile ones; blade evergreen, shiny above, paler below, midvein pale, base heart-shaped to lobed. Cher Ferns and Fern Allies 35 or slightly ascending, opposite or nearly so, margins rounded to irregularly toothed, veins running to teeth not sinuses. Sporangia: In round sori, few, scattered on lower surface. Distribution: Open woods, limestone ledges. Mostly uncommon, but locally common in some areas of the park. In Kentucky: AP, IP, ME. This fragile-looking fern is common throughout the state. It produces two kinds of leaves: the first set in early spring is small and sterile, and the second set in late May or June is much larger and fertile. Spreading by rhizomes, it makes a verdant ground cover in a few spots at Cherokee. Southern bladder fern Wood Fern Family Cystopteris protrusa (Weath.) Blasdell Dryopteridaceae Key features: Fern from creeping rhizomes that protrude forward, rhizomes with golden yellow hairs; leaves in loose clumps, triangular to broadly lanceolate in general outline. Origin: Native. Life form: Perennial, from creeping rhizomes that extend forward before the emergent leaves. Stems: Smooth, threadlike, strawcolored to green with small, tan scales near the fragile base. Leaves: Erect to slightly arching, blades 3 to 10 inches long, leaflets small, 9 to 15, at right angles to stem Cher 36 Ferns and Fern Allies stalk winged, blades net-veined, margins wavy, persisting all summer until frost; fertile leaves erect, with hard, bead-like clusters turning brown and persisting throughout winter. Sporangia: In round sori hidden by inrolled leaflets. Distribution: Wet woods along horse trail. Rare. In Kentucky: AP, IP, ME. Fossils of this fern dating back more than 60 million years show that the plants of today have changed very little in appearance over the millennia. The common name refers to the sensitivity of the sterile leaves to frost. Sensitive fern Wood Fern Family Onoclea sensibilis L. Dryopteridaceae Key features: Stems yellowish, winged above; sterile leaves with blades deeply lobed; fertile leaves are bare stalks with bead-like clusters of sporangia at the top. Origin: Native. Life form: Perennial from a stout, spreading rhizome. Stems: Base brown, scales few, usually longer than blade; to 2 feet tall. Leaves: Few, of 2 types: sterile leaves erect or ascending, deeply divided into 8 opposite, lobed pairs, light green, central Iroq [18...