Thursday, February 25, 2010

Polystichum Ferns

Polystichum
A large genus of woodland Fern that are not invasive. They prefer partial to full shade on fertile soil. They are tolerant of lime. The Polystichum Ferns responds well to frequent, light applications of fertilizer. Most Polystichums can tolerate moderate drought and are very heat and humidity tolerant. Deer resistant and insect and disease pests are rare.
Division can be done during early spring.

* photo taken on Aug 20 2011 @ Brookside Gardens, Wheaton, MD


Polystichum acrostichoides ( Christmas Fern )
An evergreen medium-sized Fern, reaching a maximum size of 3 x 5 feet, that is native to upland woods in eastern North America ( from southeast Minnesota to Wawa, Ontario to Haileybury, Ontario to Newfoundland; south to eastern Texas and northern Florida ). It is endangered in Minnesota, Wisconsin and Kansas. It has declined considerably in southern Ontario; was abundant before 1900 around Windsor. It looks great in a shaded rock garden and also planted closely for use as a woodland groundcover.
The leathery pinnate fronds, up to 36 x 5 inches, are glossy deep green in color.
The fronds typically have 20 to 25 pairs of lance-shaped leaflets.
The fronds emerge during mid spring through also randomly later in the season.
Hardy zones 3 to 9 in partial to deep shade on moist, fertile, limey or acidic ( sandy or loam ) soils on a site protected from excessive wind. It does not grow well in the western U.S. where it should be replaced with Polystichum munitum. Very tolerant of drought as well as dry shade. Pruning is limited to removal of old fronds during mid spring to neaten appearance.

* photo taken on April 11 2010 @ U.S. National Arboretum

* photo taken on April 18 2010 @ U.S. National Arboretum, D.C.

* photo taken on May 1 2010 @ U.S. National Arboretum, DC

* photos taken on Aug 25 2011 @ Scott Arboretum, Swarthmore College, PA


* photos taken on May 9 2012 in Columbia, MD

* photos taken on May 18 2013 in Columbia, MD
* photos taken on Oct 17 2013 in Olney, MD

* photo taken on May 7 2014 @ London Town Gardens, Edgewater, MD

* photos taken on May 19 2014 in Columbia, MD

* photos taken on May 6 2015 @ Cypressmeade Park, Ellicott City, MD

* photos taken on Aug 20 2016 in Olney, MD

* photos taken Aug 2016 @ Patuxent Research Refuge, Laurel, MD

* photos taken on Sep 22 2016 @ Patuxent Research Refuge, Laurel, MD

* photos taken on Sep 25 2016 near Reisterstown, MD

* photos taken on Apr 23 2017 @ Brookside Gardens, Wheaton, MD


Polystichum aculeatum ( Hard Shield Fern )
An impressive evergreen medium-sized Fern, reaching a maximum size of 4 x 3 feet, that is native to most of Europe into northern Russia ( excluding Scandinavia and most of the Mediterranean except in moist mountain habitats ). It looks great planted on a wooded site near to water.
The finely divided, rigid, leathery, pinnate fronds, up to 36 x 6 inches, are glossy deep green and have pinnae ( up to 4.3 inches ) that is deeply divided. The foliage is yellowish at first during spring. Individual fronds may live up to 2.5 years and persist on the plants long after.
Hardy zones 3 to 8 in partial to deep shade on moist limey soils.
It is recommended to prune off old fronds in early spring, however removing green fronds is not recommended and can weaken the plant.

Polystichum aleuticum ( Aleutian Shield Fern )
Native to the harsh Aleutian Islands of Alaska and only reaching up to 6 inches in height, this is one of the worlds most endangered plants. It was thought to be extinct from 1938 to 1975 when rediscovered on Adak Island. It is very likely that less than 150 plants exist in the world today. It is unlike any other North American species, but is similar to a dwarf Polystichum species located in the mountains in southwestern Asia.
The narrow lance-shaped fronds, up to 6 inches in length, are deep olive-green.
The fronds each have 15 to 25 pairs of leaflets, up to 0.3 inches in length.

* photo of unknown internet source


Polystichum andersonii ( Anderson's Sword Fern )
An attractive, evergreen fern native to cool, mountain forests in northwestern North America ( from Cordova, Alaska to southwest Yukon to near Jasper National Park, Alberta; south to Oregon to western Montana ).
Forming a short trunk, this Fern bears bipinnate fronds, up to 40 x 8 inches.
Hardy zones 5 to 6 ( Yukon clones likely much colder ), requiring a cool climate.

Polystichum braunii ( Brauns Holly Fern )
An attractive, dense, upright, semi-evergreen to evergreen medium-sized Fern, reaching a maximum size of 3.5 x 3 feet, that is native to northeastern North America ( from International Falls, Minnesota around the north shore of Lake Superior to Petawawa, Ontario to Newfoundland; south to central Wisconsin, central Michigan, southern Ontario to northeast Pennsylvania to Massachusetts ). It is also native to western North America ( from Kodiak, Alaska to southwest Yukon; to southern British Columbia and far northern Idaho. It may eventually slowly spread to form a large clump due to its creeping rhizomes. It is endangered in Idaho, Minnesota, Wisconsin, lower Michigan, Pennesylvania and Massachusetts ).
The thick, leathery, arching pinnate fronds, up to 40 x 9 ( rarely over 28 ) inches, are silvery at first, turning to glossy deep green.
The stalks are covered in golden-brown scales.
The dead older fronds are often persistant unless pruned off.
Hardy zones 3 to 6 in partial to deep shade on cool, moist, fertile sites.
Protect from late spring frosts with dry leaves or evergreen boughs.

* photo taken on March 28 2010 @ U.S. National Arboretum, D.C.


Polystichum californicum ( California sword fern )
A Fern native to western North America ( from southwest British Columbia, south to California in the coastal ranges and the Sierra Nevada ).
The arching to erect, lance-shaped fronds are up to 40 inches in length with sharply-toothed leaflets.
Hardy zones 8 to 9 in cool maritime climates in shade on moist, well drained soil.

Polystichum lemmonii ( Lemmon's Holly Fern )
An attractive, evergreen fern, native from southwest to south-central British Columbia; south to northern California. It is critically endangered in Canada where it is only known from British Columbia at Baldy Mountain area on the eastern side of the Okanagan Valley. It is found on serpentine rock outcrops in the wild.
The upright fronds are up to 16 x 2.8 inches in size. The pinnate fronds are composed of 20 to 25 oval leaflets.
Hardy zones 6 to 9 in partial shade on sandy or serpentine, very well drained soil.

Polystichum lonchitis ( Mountain Holly Fern )
An evergreen medium-sized Fern, reaching a maximum size of 3 x 5 feet, that is native to North America ( from Bethel, Alaska to Fairbanks, Alaska to central Yukon to Greenland; south into the U.S. Rockies and the Great Lakes as well as the Canadian Maritimes ). In Ontario; it is most abundant on rock outcrops on the Niagara Escarpment in Gray County and on the Bruce Peninsula. It is also native to northern Eurasia. It is excellent for cool, moist shady rock gardens and in the wild is usually found on rock outcrops shaded by deciduous or mixed woodlands.
The narrow, leathery pinnate fronds, up to 3 inches wide, are glossy deep green.
The fronds are composed of toothed, lance-shaped to oblong leaflets, up to 1.6 inches in length.
Hardy zones 3 to 6 in partial to deep shade on moist limey soils. It does not enjoy hot summers, however grows well in many mountainous regions, esp in cool conifer forests.

Polystichum makinoi ( Makino's Holly Fern )
A very attractive, vigorous, erect Fern reaching up to 2.5 x 2.5 feet, that is native to mountain forests from eastern India to southern China and Japan and the Phillipines.
The erect, triangular, evergreen fronds, up to 30 x 8 inches, are glossy deep green.
Hardy zones 5 to 9 in partial to full shade on just about any fertile, moist to wet soil. Easy to grow.
It is recommended to prune off old fronds in early spring, however removing green fronds is not recommended and can weaken the plant.

* photo taken on April 11 2010 @ U.S. National Arboretum


Polystichum munitum ( Sword Fern )
A vigorous evergreen medium-sized Fern, forming a large clump up to 6 x 6+ feet, that is native to western North America ( from Juneau, Alaska to far north-central British Columbia; south to California { along coast } to western Montana...a separate disjunct range in western South Dakota also exists }. A single plant may produce up to 100 fronds, with the clump expanding each year. It is excellent for naturalizing in the woodland understory in the Pacific Northwest.
The leathery, arching, pinnate fronds, up to 72 x 12 inches, are glossy deep green in color. The fronds can live as long as 2.5 years and the narrow-lanceolate pinnae can be up to 6 inches in length.
Hardy zones 3 to 9 in partial to deep shade on moist, fertile sites. In zones 3 to 5, only plants originating from exceptionally cold hardy seed source originating from isolated populations in interior northern British Columbia and the Black Hills in South Dakota should be used. It grows poorly in the hot humid summers of the eastern U.S. though established plants are known to even tolerate summer drought in northern California. The Sword Fern responds well to frequent, light applications of fertilizer.
It is recommended to prune off old fronds in early spring, however removing green fronds is not recommended and can weaken the plant.

* historical archive photo


Polystichum neolobium ( Long-Eared Holly Fern )
An evergreen, medium-sized Fern, forming a large clump up to 3 x 2 feet, that is native to moist woods from India to China and Japan as well as Burma & Taiwan.
The arching, pinnate fronds, up to 40 x 5 inches, are glossy deep green in color.
The leaflets are oblanceolate.
Hardy zones 3 to 9 in partial to deep shade on moist, humus-rich soils. Easy to grow.

Polystichum polyblepharum ( Japanese Tassel Fern )
An evergreen medium-sized Fern, reaching a maximum size of 4 x 6.6 ( rarely over 3 x 4 ) feet, that is native to eastern China, Korea and Japan.
The very showy, tassel-like, leathery fronds, up to 40 x 10 inches, are glossy deep green. The lance-shaped to oblong leaflets are up to 5 x 1.5 inches in size.
The leaflets are often prickly tipped.
Hardy zones 5 to 8 in partial to full shade on moist, fertile soil.
Prone to late spring frosts. Easy to grow.

* photos taken on May 6 2010 @ Brookside Gardens, Wheaton, MD

* photos taken on annual Horticultural Society of Maryland Garden Tour

* photo taken on Aug 25 2011 @ Scott Arboretum, Swarthmore, PA

* photo taken on April 27 2012 in Columbia, MD
* photo taken on Oct 17 2013 in Olney, MD


Polystichum polysepalum

* photo taken on May 8 2010 @ U.S. National Arboretum, D.C.


Polystichum retrosopaleceum
A rare, deciduous to evergreen ( depending on climate ) Fern, reaching up to 3.5 feet in height, that is native to forests of Japan.
The erect fronds, up to 40 x 12 inches, are lustrous polished deep green with downward pointing pinnae.
The stalks are heavily scaly.
Hardy zones 4 to 8 in shade where it is easily grown.


* photo taken on May 8 2010 @ U.S. National Arboretum, D.C.


Polystichum rigens ( Rigid Holly Fern )
A very handsome, evergreen Fern, reaching up to 2.5 ( rarely over 2 ) feet in height, that is native to mountain forests of China and Japan.
The rigid, leathery, triangular fronds, up to 30 x 8 ( rarely over 20 ) inches, are bright green at first, turning to glossy deep green.
Hardy zones 4 to 8 in partial to full shade on moist, fertile, acidic soil. Established plants are drought tolerant.

Polystichum scopulinum ( Rock Sword Fern )
A small, semi-evergreen Fern that is native to south-central British Columbia, much of the western U.S. and with a separate range on the Gaspe Peninsula in Quebec and in western Newfoundland where it is now presumed extinct. It is found only on serpentine rock outcrops in the wild and is considered critically endangered in Canada.
The erect narrow, lance-shaped pinnate fronds, up to 20 x 2.5 inches, are mid green.
Each frond is composed of toothed, lance-shaped or oblong leaflets up to 1.3 inches in length.
Hardy zones 2 to 6, being fully deciduous in zone 2 and 3.

* photo of unknown internet source


Polystichum setiferum ( Soft Shield Fern )
A vigorous, semi-evergreen medium-sized Fern, reaching a maximum size of 5 x 5 feet, that is native to Europe from Scotland to the Caspian Sea; south to the Mediterranean ( at high elevations ). It is most common in southwest Europe where it luxuriates in year round moisture. Soft Shield Fern is also a widespread native to western British Columbia and in coastal Alaska to the east and south of Seward.
The graceful, arching, leathery, numerous pinnate fronds, up to 60 x 10 ( rarely over 36 ) inches, are mid to deep green, with delicately cut pinnae.
The fronds are composed of leaflets, up to 5.6 ( rarely over 4 ) inches in length.
The leaflets are prickly-tipped.
The individual fronds live up to 1.5 years and persist after withering.
Hardy zones 4 to 8 in partial to deep shade on moist or dryish, fertile soils. Easy to grow and tolerant of high PH soils. Prefers a humid climate. It is recommended to prune off old fronds in early spring, however removing green fronds is not recommended and can weaken the plant.

* historical archive photo


'Congestum Cristatum' ( Crested Shield Fern )
Forms a dense clump up to 1.6 x 2.5 feet with upright, crested fronds with overlapping segments.

'Dahlem'
Forms a semi-evergreen clump, up to 2.5 x 2.5 feet, with erect, arching, glossy mid-green, lance-shaped, bipinnate fronds.

'Divisilobum'
Ferns very finely divided.

'Herrenhausen'
Forms an evergreen clump up to 4 x 3 feet with bright green parsley-like, densely-frilled fronds.

'Plumosum'
Reaches up to 3 x 3 feet with soft feathery fronds that are light green.

'Proliferum' ( Soft Shield Fern )
Reaches up to 5 x 5 feet, with long, pointed, deep green fronds that are arranged in a spiral around the crown.

Polystichum tripteron ( Trifid Holly Fern )
A semi-evergreen to evergreen Fern, reaching up to 2.5 x 3 + feet, that is native to mountain forests of eastern Siberia, Manchuria, Korea and Japan.
The fronds are up to 28 x 4 inches. The new fronds all appear during early spring.
Hardy zones 5 to 8 ( likely colder than 5 with winter mulch )

* photo taken on May 8 2010 @ U.S. National Arboretum, D.C.

* photo taken on May 1 2010 @ U.S. National Arboretum

* photos taken on June 23 2013 @ U.S. National Arboretum, DC


Polystichum tsus-simense ( Korean Rock Fern )
A moderate growing, compact, evergreen Fern forming a vase-shaped clump up to 2 x 2 feet, that is native to China, Korea & Japan; south to Indonesia. Looks great with Hostas, esp 'Francis Williams'.
The leathery, triangular fronds, up to 24 x 8 ( rarely over 16 ) inches, are purplish at first, turning to glossy deep green.
The stems are black. It is an excellent plant for a shaded rock garden.
Hardy zones 3 to 8 in partial to deep shade on moist, fertile soil.
It will tolerate the occasional drought. Prefers protection from excessive wind during winter.

* photo taken on May 8 2010 @ McCrillis Gardens, Bethesda, MD

* photo taken on Dec 2011 in Columbia, MD

* photo taken on Oct 6 2012 in Columbia, MD

* photo taken @ Smithsonian Inst, Wash., DC on Aug 25 2014


Polystichum vestitum ( Prickly Shield Fern )
A semi-evergreen to evergreen Fern native to Chatham Islands, New Zealand and its subantarctic Islands.
It is differnt than most Polystichum Ferns in that it may form a trunk up to 28 inches in height. The fronds, up to 5 feet x 10 inches, are glossy deep green with the stems covered in brown hairs.
Hardy zone 9 in coastal maritime climates only.

* photo of unknown internet source

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