Blechnum amabile (lovely), with a short-creeping rhizome, produces 1- to 2-ft. (30- to 60-cm) once-pinnate, evergreen, dimorphic fronds approximately equal in length on short
stipes. The blades are frequently pinkish in new growth and taper at the base. Fertile fronds have constricted pinnae. This species is rarely available commercially, but is similar to B. niponicum differing in having a creeping rather than an erect rhizome and in the more obscure characteristic of ovate rather than linear stipe scales. A native of Japan, it grows in partial shade in cliff crevices and well-drained rocky sites in the mountains or forests. When available it should adapt in moist, crumbly soil in the shady sites of Zones 7 and 8.
Blechnum auriculatum (eared), classified by some authors as B. australesubsp. auriculatum, grows from 1 to 2 ft. (30 to 60 cm) and has once-pinnate fronds with the pinnae eared adjacent to the rachis. The sterile and fertile fronds are similar and subevergreen. Native to South America, this species creeps slowly, looking almost like a Nephrolepis. It is cultivated in Zone 8 central England.
Blechnum australe (of the south) is an evergreen with dimorphic 2-ft. (60-cm) fronds. Sterile fronds are once-pinnate and elliptic with reduced basal pinnae. Fertile fronds match the sterile in the lower portions and have narrow linear spore-bearing pinnae from the waist up. An African native, this species prefers filtered light and will spread with restraint in perpetually moist sites in Zones 8 and 9.
Blechnum blechnoides (like a Blechnum) from New Zealand and Chile is, like many blechnums from Down Under, brilliantly enhanced with red new foliage. It is dimorphic with 9-in. (23-cm) sterile, zigzagged fronds and smaller fertile fronds with widely spaced narrow pinnae. Commonly called the salt spray fern, it grows in nature in coastal areas and is suited for comparable areas in Zones 9 and 10 along the U.S. west coast from the California redwoods south.
Blechnum cartilagineum (like cartilage), the gristle fern, is an Australian with outlying populations in the Philippines, New Guinea, and India. It colonizes in swamps and on marshy streambanks. Monomorphic, leathery 2- to 4-ft. (60- to 120-cm) fronds, with metallic, bronze to pinkish new growth, are once-pinnate with pointed pinnae. In spite of its native haunts, it is more accepting of dryish conditions than other blechnums and should acclimate in Zones 9 and 10 or in transitional greenhouse regions between the humid and "normal" atmosphere sections.
Blechnum chambersii (after Thomas Chambers, director of the Royal Botanic Gardens, Sydney, Australia), lance water fern, is native to damp and rather dark sites in New Zealand, Australia, Fiji, and Samoa. With its erect dimorphic fronds, it adds to decorative waterside options in Zones 9 and 10. Arching lanceolate swoops of 2- to 3-ft. (60- to 90-cm) rose-enhanced emerging foliage which gradually mature to a glossy dark green are comfortable in moist to wet shade.
Blechnum colensoi (after William Colenso, 1811-1899), Colenso's hard fern, or the waterfall fern, is a dimorphic New Zealand endemic with short-creeping rhizomes. Deep blackish-green, pendulous sterile fronds, all terminating in a needlelike "drip tip" point, are variable from undivided to kL V
Young pink fronds on Blechnum cordatum growing in Ecuador. Photo by Joan Eiger Gottlieb.
broadly elliptical with the latter divided into several pinnate pinnae. The fertile fronds have a few long wispy threads of pinnae. This species is suitable for deep shade and wet soil in Zone 9 or as a sultry understory in the humid rainforest section of conservatories.
Blechnum cordatum (heart-shaped), from the high-elevation, 5,000- to 10,000-ft. (1500-to 3000-m) cloud forests of Columbia, Peru, Venezuela, Bolivia, and Ecuador (note not from Chile), is a tall dimorphic species with ruby new growth. It is extremely closely allied botanically with B. chilense although the two species are separated in nature by hundreds of miles. The easiest observable difference is that B. cordatum pinnae do not have the lower lip of the pinnae overlapping the rachis. In addition, Mickel and Smith (2004) observe, "B. cordatum... widespread and common in South America and with many syn-
The fronds of Blechnum filiforme clamber up a tree in New Zealand.
Small fronds of Blechnum gayanum colonize against a log in the Gassner garden.
onyms,is very closely related to B. schiedeanum [ofMexico] and perhaps not distinguishable. Monographic study is needed on this group of blechnums before names can be applied with confidence." To which my colleagues and I say, "Amen."
Blechnum filiforme (threadlike), the thread fern, is a climbing plant with miniature 2- to 6-in. (5- to 15-cm) juvenile fronds romping about indiscriminately, vinelike, in the bush country and on the forest floors in New Zealand. When it encounters a tree, the species continues its opportunistic viney inclination and spirals upward, gaining in girth as it gains in altitude eventually cloaking the entire host tree. The creeping young fronds are sterile. The mature fronds, festooning the treetops, sometimes reach 2 ft. (60 cm) in length. The adult population produces both fertile and sterile fronds with the slender fertile ones being the threads of the common name. This unconventional attraction for Zone 8 and 9 woodlands is a potential conversation piece for fern enthusiasts in the moisture-laden coastal gardens of the Pacific Northwest and even more so along the Gulf Stream-tempered Atlantic rim of the British Isles. The migrating juvenile stems prefer to be rooted in heavy soil, and the upwardly mobile fronds need an arboreal climbing gym for complete success. Basket culture is an excellent option. This species can be propagated by carefully executed division as well as by spores.
Blechnum gayanum (after French botanist Jacques Gay), synonym B. microphyllum, is a dense, dimorphic little bushlet of a fern from the mountains of southern Chile and Argentina. Crowded bunches of sterile fronds mature at 6 to 8 in. (15 to 20 cm) in the shadow of slightly taller fertile fronds. This species prefers bright light and dampish acid soil in Zones 7 to 9. Plant it in your favorite prominent site, be it rock garden, container, or woodland foreground. As with other miniatures it is especially appropriate for display at eye level.
Blechnum gibbum (humped, referring to the swollen stipe), the "dwarf tree fern" from the South Pacific Islands, is an appropriate fern for gardens, greenhouses, and conserva-
A slender trunk supports the fronds of Blechnum gibbum in the Fernery at the Morris Arboretum.
tories that provide the signature tropical humidity and warmth of its South Seas homeland. Bright green swirls of evergreen 2-ft. (60-cm) fronds are dimorphic and arise from a stout rhizome that may in time form a small trunk. For household use it needs well-aerated but consistently moist soil. 'Silver Lady' is a cultivar that has done well in California.
Blechnum magellanicum (from the Straits of Magellan) is a would-be tree fern from southern Chile and Argentina. Once-pinnate dimorphic fronds produce towers of cycadlike foliage. The rhizome can form a trunk of up to 4 ft. (1.2 m) in lowland habitats. At higher altitudes, the trunk is absent, presumably since the colder exposures render it vulnerable to the desiccation and vagaries of alpine weather (and there is no one there to tenderly apply a protective wrap). In the past this
species has been confused with B. chilense, which does not have a trunk. In addition, the foliage of B. magellanicum is shiny and the pinnae are stalkless. Spores of this species are short-lived, but plants, by contrast, are statuesque additions to Zone 9 and protected Zone 8 gardens.
Blechnum minus (small) is a swamp-loving species, which comes in two manifestations and much nomenclatural confusion, from New Zealand and Australia. The New Zealander, which upon further study may be reclassified as B. procerum, is nurtured successfully in Britain whereas the Australian is reputed to be difficult to establish. Both are dimorphic with oval sterile fronds and spidery fertile fronds.
Blechnum orientale (of the East) grows in Japanese lowlands (as weeds according to Iwatsuki et al. 1995) and the tropics in huge 3- to 5-ft. (90- to 150-cm) bushels of rosy, once-pinnate fronds. It is a showstopper in the humidity of greenhouses, conservatories, and lanai sides in the lush banana belts of Zones 9 to 11. Think Hawaii—with colorful cascading fronds in hotel lobbies, elegant entryway approaches, and let loose the travel appetite.
Blechnumpatersonii (for William Paterson, 1755-1810), the strap water fern, synonym Stegania patersonii, is from Australia, New Zealand, the Philippines, and South Pacific Islands. It has atypical (for a Blechnum) undivided, simple, 12- to 18-in. (30- to 45-cm) "straps" of sterile fronds. Fertile fronds with matching, straplike bases branch into several pairs of pinnae and finish with an extended tip. Often pendulous with bronzy new growth, this fern enjoys the streamside comforts of continually moist, rich soil in light to deep shade and should adapt accordingly in Zone 9 gardens or elsewhere in greenhouses. Once established, it does not like to be disturbed.
Blechnum procerum (extended, tall) is a dimorphic New Zealand native with a short-creeping rhizome. The oblong, sterile blades emerge in shades of bronze and have a long stipe and three to eight pairs of pinnae embracing an extended tonguelike apical tip. In its native haunts, ranging from subalpine scrub, where it is common, to bogs, where it is not, it reaches 2 to 3 ft. (60 to 90 cm). Unlike the drooping sterile fronds, the fertile fronds are upright and slightly taller. This species adapts to life in the open and comes recommended as a ground cover for Zones 8 (where it needs to be tested for prolonged cold tolerance) and 9.
Blechnumpunctulatum (with small dots), the glossy hard fern, is a variable species from South Africa with dimorphic 2-to 3-ft. (60- to 90-cm) fronds widely spaced on a stoloniferous base. Linear to lanceolate sterile blades are once-pinnate with crowded unstalked pinnae. Fertile fronds have sori running the length of the linear pinnae. Red new growth adds elegance and interest to this species. It is cultivated in light shade and rich soil in Zone 7 German gardens. Commercially, it is popular in the cut flower trade.
Blechnum tabulare (from Table Mountain above Cape Town, South Africa) has for years been lumped into the confused horticultural kettle of assorted Southern Hemisphere blechnums. This is an upright, evergreen species with strongly vertical fertile fronds erupting from the center of leathery sterile fronds. It can form a small trunk, taller in high rainfall areas, and has pinnae, which are reduced in size on the fronds' lower portions. Pinnae bases are unique in being unequally shaped with a notch on the lower side. The undersides are embellished with tawny hairs. This species is recommended as a centerpiece for humid shade or container planting in Zones 9 and 10.
Blechnum vulcanicum (of volcanic soils), wedge water fern, is dimorphic with narrowly triangular, once-pinnate, somewhat hairy, sterile fronds pointing their basal pinnae downwards. Both sterile and fertile fronds, of up to 2 ft. (60 cm), have long stipes of one-half of the frond length. With bronzy new growth, this species is frequently seen as an attractive drapery on moist banks in the South Island of its native New Zealand. It is also found in Australia and the Pacific Islands and is a decorative addition in moist to wet Zone 9 gardens. Ideally (and perhaps optimistically) it is also a candidate for the sheltered niche in Zone 8.
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