Native Ferns
Total Page：16
File Type：pdf, Size：1020Kb
Europe,” explains Moran. “That is basically The western counterpart of this species why the plant species that occur in these is A. aleuticum (Zones 3–8, 8–1), which has regions are similar today.” asymmetrical fronds with elongated pinnae In this article, I am focusing on the North that resemble fingers. Jones says that many American range of each species. commercial growers do not differentiate between A. pedatum and A. aleuticum. “I FERN TERMINOLOGY find the latter to be a more variable species Ferns are grown for their foliage; in fact, that occurs in a wider range of environ- they produce no flowers at all (see “Fern ments, making it an excellent choice for a Reproduction,” opposite page). They also wide climate range. It is well worth the time have their own taxonomic terminology. to establish it,” says Jones. A frond is a complete leaf, composed For adaptability, you can’t beat Christ- of a stalk, called a stipe, and the blade, mas fern (Polystichum acrostichoides, Zones which is often dissected into leaflets called 3–8, 8–1), whose stiff evergreen fronds form pinnae (singular, pinna). The unfurling dense, dependable clumps in a variety of fronds are called crosiers or fiddleheads. settings. “There are few truly evergreen ferns hardy in the Northeast, but Christ- DIVERSE HABITATS mas fern comes awfully close,” says Wil- Ferns grow wild in varied settings, from open woodlands, swamps, and dappled banks, to bare cliff faces, shel- FERN REPRODUCTION tered overhangs, and along the margins Most ferns flourish in moist soils, not of pounding waterfalls. Among the simply because they require constant ground-dwellers are the best all-around moisture, but because they demand garden ferns. Most are readily obtained water for reproduction. Ferns reproduce and easy to grow. Many of the choic- from spores, not seeds. Unlike seeds, est rock ferns are best left to experts, al- spores germinate not into seedlings, though a few are good garden performers but into an intermediate stage called (see the chart on page 33). By far the most popular garden ferns are those with evergreen foliage. So much so that veteran fernophile, Judith Jones, who Native Ferns owns Fancy Fronds Nursery in Gold Bar, Washington, laments that it is impossible Maidenhair ferns like these flanking a water feature at the Butchart Gardens on Vancouver Adapted to diverse regions of North America, native ferns draw to sell a deciduous fern. That is a shame, Island, British Columbia, thrive in a shady, consistently moist site. as deciduous and semi-evergreen ferns are gardeners into the shade with their soothing green hues and standouts in the spring and summer gar- the shallow roots of sufficient nitrogen for If you weigh beauty, adaptability, and den. They maintain good foliar constitu- healthy growth. Ferns take a year or two ease of culture in a variety of garden situ- intricately patterned foliage. BY C. COLSTON BURRELL tion with minimal care as long as the soil to become established, and this period is ations, the cream rises quickly to the top. stays moist. During severe drought, plants critical to the success of plantings. Consis- The crème de la crème has to be North- may defoliate but will re-sprout when suf- tent moisture is needed until young trans- ern maidenhair fern (Adiantum peda- RIZED FOR their filigreed foli- eastern North America, eastern Asia, and ficient water is restored. Many species pres- plants develop enough roots and rhizomes tum, USDA Hardiness Zones 3–8, AHS age, ferns add texture and grace- western Europe,” says Robbin C. Moran, ent russet, yellow, or straw-colored fronds to tolerate drought. Heat Zones 8–1), which presents elegant Rather than seeds, ferns reproduce with Pful motion to gardens and glades. curator of botany at New York Botanical once nights become frosty. sea-green, horseshoe-shaped fronds atop spores like these rust-colored ones on Some gardeners may equate their dainty Garden and author of A Natural History TOP CHOICES ebony stipes. The one- to two-foot decid- the undersides of Christmas fern fronds. appearance with a fussy nature, but plen- of Ferns (Timber Press, 2009). MOISTURE REQUIREMENTS The characteristics of some of the most uous fronds dance in the slightest breeze. ty of native species adapt well to garden This overlap resulted from the migra- While some ferns require consistently tough, indestructible ferns are thick wa- Plant it in groups or drifts in woodland the gametophyte generation, that pro- culture. When properly chosen and sited, tion of flora southward from high northern moist, or even wet soil to look their best ter-storing rhizomes, leathery evergreen gardens, under shrubs and flowering duces a small, filmy prothallus, which these ferns will enliven shady spaces with latitudes some 55 million years ago. “As the throughout the growing season, the ma- fronds, and a tenacious root system. trees or with other ferns as a foundation bears both the male and female sex or- their forms and subtle hues. earth’s climate cooled and became more jority of ferns, once established, are quite These qualities are typical of many ferns planting. When allowed to cascade down gans. It is here that water is critical to In discussing ferns native to North seasonal in the latter half of the Tertiary drought tolerant. That said, prolonged in two genera—Dryopteris and Polys- a slope, it looks like a green waterfall. The the survival of the fern, as fertilization America, it’s important to understand Period, the once-continuous circumbore- water deprivation will induce dormancy tichum—which I will be highlighting delicate pink fiddleheads combine well can only occur when the sperm cells that many of our “natives” are also found al flora migrated southward and became or can even be fatal. along with other good garden ferns on with spring-flowering bulbs and wild- can swim freely on a film of water to in other parts of the world. “There is a fragmented into three great blocks: eastern Plant ferns in water-retentive soil the following pages. (For regional rec- flowers. It prefers moist, nearly neutral reach the egg cells. After fertilization, a lot of overlap of the same species between North America, eastern Asia, and western amended with compost. The addition of ommendations for native ferns, visit the (pH between 6.5 and 7.5), humus-rich young plant is produced that eventually a light organic mulch helps conserve mois- AHS website and follow the link to the soil in part to full shade, and is native to grows into a fern. —C.C.B. The stately fronds of Goldie’s wood fern may reach three or four feet in length. ture, but a heavy bark mulch may deprive MICHAELS. THOMPSON LEFT: MARKTURNER. RIGHT:SAXONHOLT web special for this article.) eastern North America. 30 the American Gardener May / June 2016 31 liam Cullina, executive director of Coastal Maine Botanical Gardens and author of FERNS FOR WET SOILS Native Ferns, Moss & Grasses (Houghton A small group of desirable ferns tolerate or demand constant moisture, and a few will even grow in standing water. Mifflin, 2008). The cast-iron character of this eastern and central North American Name Height/Spread Ornamental Attributes Native Range USDA Hardiness Zones, native adapts to clay soil or humus. Giv- (inches) in North America* AHS Heat Zones en a little shade, it is well behaved, long Adiantum capillus-veneris 12–24/12–18 Deciduous, cascading triangular, Southern U.S., west 7–10, 11–7 lived, and increases in beauty with time. (Southern maidenhair fern) fronds chartreuse to sea green, to California “In bright light, the narrow, 12- to 16-inch fan-shaped pinnae fronds are carried nearly vertically, while Dryopteris carthusiana 18–30/18–30 Glossy, semi-evergreen fronds Canada, northern U.S., 2–7, 7–1 in deep shade they splay out horizontally,” (Spinulose wood fern) are deeply dissected, emerging south to South Carolina says Cullina. The stiff fronds remain erect in a tall arching vase from a and west to Missouri until hard frost or heavy snow pushes them stout rhizome over. Combine Christmas fern with other Dryopteris ludoviciana 24–48/24–36 Stiff, erect narrow fronds, Southeastern coastal 6–9, 9–5 ferns in foundation plantings, along walks (Southern wood fern) tapered at both ends, are plains west to Texas and steps, or in woodland gardens with evergreen in mild climates bulbs, wildflowers, and groundcovers. Onoclea sensibilis 12–30/24–48 Deciduous chartreuse sterile Eastern and central North 4–9, 9–1 At first glance, silvery glade fern (De- (Sensitive fern) fronds form carpet; fast-creeping America, from Labrador paria acrostichoides, Zones 4–8, 8–1) may rhizomes; beaded fertile fronds and Manitoba, south to look like many other ferns, with its decid- persist through winter Florida and Texas uous, moderately dissected fronds, but a Osmunda cinnamomea 24–60/24–48 Statuesque deciduous fern with Eastern North America 3–9, 9–1 second look reveals a tidy, medium green Christmas ferns have coarsely textured fronds that remain evergreen through winter. (Cinnamon fern) arching sterile fronds that emerge Labrador to Ontario, clump with arching fronds clustered on a after the cinnamon-colored south to Florida slow-creeping rhizome. The fronds open erable sun if the soil stays moist. Silvery looks stunning in the shade garden among spore-bearing fronds and Texas chartreuse and fade to green with age. glade fern is native from Nova Scotia and drifts of wildflowers or bold-leaved plants Osmunda regalis 24–60/24–48 Tall, deciduous fronds emerge Newfoundland and 2–10, 9–1 Since fronds are produced in succession Ontario, south to Georgia and Arkansas.