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The Ferns and Fern Allies of Jefferson County, Kentucky

Jefferson County, Kentucky, is in north-central Kentucky, on the western side of the Cincinnati Arch, an anticlinal geologic structure that extends from Indiana and Ohio through Kentucky and Tennessee. The eastern two-thirds of the county is in the Bluegrass area of central Kentucky, comprising Ordovician and Devonian limestones, dolomites and shales, with the limestone predominating. The northwest, far west, and southwest extremes of the county are river plains and terraces bordering the Ohio River. An area in the west-central county is a slack-water flat, a remnant of a large glacial lake, and which was a large swamp prior to settlement of the area by the Europeans. The western half of the extreme southern area of the county is in the Knobs, a geological escarpment representing the transition from the higher and younger Pennyrile to the west and south, to the lower and older Bluegrass to the east. The Knobs comprise principally siltstone and shale, and include the area of the Jefferson County Memorial Forest.

Kingdom: Plantae

Divison: Lycopodiophyta

Class: Lycopodiopsida

Order: Lycopodiales
Family: Lycopodiaceae: the clubmosses

Genus: Diphasiastrum

Diphasiatrum digitatum: ground-cedar or running-cedar

Frequent throughout the county in old fields and young woods, often forming extensive colonies, especially in redcedar groves in the Bluegrass area.

Order: Selaginellales
Family: Selaginellaceae: the spikemosses

Genus: Selaginella

Selaginella apoda: meadow spikemoss

Rare, in open, grassy, moist bottoms where the overgrowth is not tall. Known in the county only from the Knobs, in the County Forest Area. Particularly to be seen at Tom Wallace Recreation Area. Easily overlooked.

Division: Polypodiophyta

Class: Equisetopsida: the horsetails and scouring-rushes

Order: Equisetales
Family: Equisetaceae: the horsetails and scouring-rushes

Genus: Equisetum

Equisetum arvense: the field horsetail or shavegrass

Occasional in moist, open fields and other areas, especially in stream bottoms.

Equisetum hyemale var. affine: scouring-rush

Frequent in the western river flats of the county, especially in sandy soil.

Class: Ophioglossopsida

Order: Ophioglossales
Family: Ophioglossaceae: the adders-tongues

Genus: Ophioglossum

Ophioglossum pycnostichum: adders-tongue

Usually dying down by early to mid-summer, occasional in bottomland thickets and easily overlooked.

Genus: Sceptridium

Sceptridium dissectum (aka B. obliquum): oblique grape-fern

Frequent, in young woodlands, found in the County Forest as well; often associated with Diphasium digitatum.

Genus: Botrypus

Botrypus virginianum: rattlesnake fern

Common, found in rich soils, especially woodland borders; found in the County Forest.

Class: Polypodiopsida

Genus: Osmunda

Osmunda claytoniana: interrupted fern

Occasional in the County Forest area only, favoring moist hillside pockets in the forest.

Genus: Adiantum

Adiantum pedatum: maidenhair fern

Frequent throughout the county, including in the County Forest; in moist, wooded valley bottoms and sometimes on moist limestone faces.

Genus: Pellaea

Pellaea atropurpurea: purple-stemmed cliffbrake

Occasional on limestone outcroppings in the eastern county; a hybrid offspring with P. glabella as one parent, not sexually fertile but reproducing by apogamous spore

Pellaea glabella: smooth cliffbrake

Occasional on limestone outcroppings in the eastern county, in more exposed locations than P. atropurpurea; one of the parents of the hybrid P. atropurpurea

Genus: Pteridium

Pteridium aquilinum: bracken

Probably the most common fern in the world, but only occasional in Jefferson County, including the County Forest; growing in open fields and open woods situations

Genus: Asplenium

Asplenium platyneuron: ebony spleenwort

Common, growing throughout the county in a wide variety of situations, including the County Forest; especially found in old fields but including rock and stonework.

Asplenium rhizophyllum (aka Camptosorus rhizophyllus): walking fern

Common, found on densely mossy rock, often forming extensive colonies on mossy limestone, often to be seen in the small stream gorges of the eastern county; once collected from the County Forest but not now known there.

Asplenium ruta-muraria: wall-rue

Rare, found in crevices on hard, well-weathered limestone in somewhat dry locations.

Genus: Athyrium

Athyrium asplenioides: southern lady fern

Frequent throughout the county, including the County Forest; favoring wet bottoms.

Diplazium pycnocarpon (aka Athyrium pycnocarpon): narrow glade fern

Common throughout the county, especially in the County Forest, often forming extensive colonies; favoring open, moist hillsides.

Deparia thelypterioides (aka Athyrium thelypterioides): silvery glade fern

Frequent throughout the county, especially in the County Forest; favoring moist slopes and streambanks.

Genus: Cystopteris

Cystopteris bulbifera: bulblet fern

Common in the eastern county, growing in moist crevices in limestone.

Cystopteris protrusa: lowland fragile fern

Common throughout the county, including the County Forest, often forming extensive colonies on moist hillsides and stream bottoms, usually disappearing by middle to late summer.

Genus: Woodsia

Woodsia obtusa: blunt-lobed cliff fern

Frequent throughout the county, including the County Forest; usually growing in crevices of dry to moist rock in the eastern county, usually growing in scree high on slopes in the County Forest.

Genus: Onoclea

Onoclea sensibilis: sensitive fern

Common throughout the county, especially the central slack-water flats but including the County Forest; probably the commonest fern in the county; favoring open, sunny, wet areas.

Genus: Thelypteris

Thelypteris noveboracensis: New-York fern

Frequent throughout the county, especially in the County Forest; growing in moist stream bottoms in woodlands.

Genus: Phegopteris

Phegopteris hexagonoptera: broad beech fern

Common throughout the county, including the County Forest; growing in a variety of woodlands.

Genus: Dryopteris

Dryopteris carthusiana (aka D. spinulosa): spinulose wood fern

Rare in the county, currently known from only one hillside location in the County Forest.

Dryopteris goldiana: Goldie's wood fern

Rare in the county, currently known from one colony in the County Forest; found in moist stream bottoms in rich soil.

Genus: Polystichum

Polystichum acrostichoides: Christmas fern

Common throughout the county, including the County Forest; found in a wide variety of situations, but particularly near the bottoms of steep, wooded slopes.

Other Ferns and Fern-Allies Once Collected in Jefferson County, But Not Now Known to Exist:

Huperzia lucidula (aka Lycopodium lucidulum): shining clubmoss

Known from one old collection near the intersection of South Park Road and I-65; favoring moist, acid seeps.

Osmundastrum cinnamomeum: cinnamon fern

Formerly common in acid, swampy areas of the county; no longer known to exist in the county.

Osmunda regalis: royal fern

Once very common in the central swamps and wetwoods of Jefferson County; no longer known in the county.

Polypodium polypodioides: resurrection fern

Known from a few places on limestone rock in the eastern county; usually growing on semi-exposed limestone in this area but also occasionally on trees; likely still to be found in the county.

Polypodium virginianum: the Virginia rock-cap fern

Known from one old collection along Bearcamp Road in the County Forest area; favoring the tops of sandstone rock shelves.

Dennstaedtia punctilobula: hay-scented fern

Known from one old collection near Penile Road in the County Forest area; favoring moist open fields.

Asplenium pinnatifidum: pinnatifid spleenwort

Known from one old collection in the County Forest area; favoring pockets in weathered sandstone.

Asplenium trichomanes: maidenhair spleenwort

Known from one old collection on Holsclaw Hill in the County Forest; favoring crevices in well-weathered limestone or sandstone.

Dryopteris intermedia: intermediate wood fern

Known from one old collection near Bearcamp Road in the County Forest area; favoring moist, acid rock in shaded locations.

Dryopteris marginalis: marginal wood fern

Known from one old collection near Bearcamp Road in the County Forest area; favoring moist, acid rock in shaded locations.

Lorinseria areolata: net-vein chain fern

Never collected but one plant was found in wet woods off McCauley Lane in the Okolona area; however, it died in the summer drought in 1988. Probably once more widespread, although never collected.

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This page was last revised on May 14, 2008.