When it comes to bold statements in the garden, few ferns can compete with the upright stature and immense size of a mature, well-grown Royal Fern or a stunning carpet of green provided by the plumes of American Ostrich Fern. We have combined two unrelated groups of plants here because their use is similar and aside from Sensitive Fern, their appearance is also very similar. Matteuccia and Onoclea are members of the family Onocleaceae; Osmunda, Osmundastrum and Claytosmunda are in the family Osmundaceae.
Matteuccia is a genus of only 3 deciduous species of ferns that are named for Carlo Matteucci (1811-1863), a physicist and politician in Florence, Italy. The genus is distinctive because it forms an upright ‘shuttlecock’ shape, and each frond has an ostrich-plume outline. The fiddleheads are edible and are a favorite in Japan as well as being the popular in New England. This genus produces two distinctive types of fronds The sterile fronds and the fertile fronds, which are highly modified are hardened and which persist throughout the winter.
Onoclea are known as sensitive ferns because they are among the first plants to respond by completely going dormant with the slightest frost. Much like the related Ostrich Fern, this one produces dramatically different fertile fronds that have pinnae that resemble a cluster of grapes—actually rolled fertile pinnules. These fertile fronds are also hardened and last throughout the winter. Onoclea is a serious runner and produces elongate rhizomes so give it room to roam.
Osmunda was at one time considered to contain the now distinct genera Claytosmunda, Osmundastrum and Plenasium. The genus name Osmunda comes from ‘Osmunder the Waterman’, the Saxon equivalent of the Norse god Thor, who according to mythology hid his family from danger in a tall clump of these ferns. All these ferns are distinctive in having large fronds arranged around an upright rhizome that seldom branches.
They tend to be large, elegant ferns, and in ideal conditions, can reach up to 6’ tall. Today, the royal ferns are the sole representatives of the genus known as Osmunda. These ferns have fertile fronds with lower pinnae that look like the sterile fronds but upper pinnae that are distinct and produce spores which quickly degrade once the spore is released. Osmunda is now a genus of about 7 species of ferns that mostly look like our familiar American Royal Fern (Osmunda spectabilis). The genus ranges throughout most of the north temperate region and also occurs in South America, and Africa. Most members of the genus are deciduous but some tender species such as Osmunda lancea are evergreen. The members of the family Osmundaceae produce spores which are photsynthetic and require rapid germination to produce the next generation.
Claytosmunda is represented by a single species Claytosmunda claytoniana with an American variety and an Asian variety (var. vestitum). These ferns are appropriately known as interrupted ferns because the fertile fronds have upper and lower pinnae that look similar to the sterile frond pinnae, but the middle pinnae are highly modified and produce the spores and wither very quickly, leaving an interrupted look to the frond.
Osmundastrum is likewise represented by a single species, Osmundastrum cinnamomeum with two varieties, the typical variety is found in North America while the Asian one (var. asiaticum) is unsurprisingly found in eastern Asia. These ferns produce very highly modified fertile fronds with the pinnae tightly congested and appressed to give the appearance of a cinnamon stick – hence the common name Cinnamon Fern.
Claytosmunda claytoniana (Interrupted Fern) This great, but rarely available native fern is found growing in moist woods from MN south to GA. The upright growing vase-shaped deciduous clump looks a bit like Cinnamon Fern, except that the normal fronds along the stipe are suddenly "interrupted" by a few brown fertile fronds. These ferns thrive where nighttime temperatures are cool and may struggle in our muggy summers in the coastal plain and piedmont of the Southeast. (Hardiness Zone 2a-8a)
Matteuccia orientalis (Oriental Ostrich Fern) This difficult to find but stunning fern makes a 4’ wide x 3’ tall clump of huge cutleaf foliage. In late summer, the clumps are topped with attractive upright fertile fronds in the center of the crown. (Hardiness Zone 7a-10b, possibly much colder)
Matteuccia struthiopteris 'The King' (The King Ostrich Fern) This amazing selection of ostrich fern is the first we have trialed which thrives in the hot, humid South, where most ostrich ferns don’t fare well. The 3' tall deciduous rosettes (6' tall under ideal conditions) spread vigorously via underground rhizomes. In nature, these ferns are found in moist ditches and lowlands, but adapt well to drier garden conditions, where they grow a bit shorter. The plants are highlighted by the 18" brown fertile fronds that appear late in the season and persist through the winter. (Hardiness Zone 4a-8a)
Matteuccia struthiopteris var. pennsylvanica (Pennsylvania Ostrich Fern) This is a wonderful native for naturalizing! Ostrich fern spreads quickly with new ferns sprouting up every few feet along the rhizome. Pennsylvania Ostrich Fern resembles Cinnamon Fern in shape, with a center fertile frond. Great for covering large tough areas... wet or dry! In climates with hot days and warm nights, the height is about half of its size in cooler regions, if it survives at all. (Hardiness Zone 4a-7a)
Onoclea sensibilis ‘Supersize’ (Supersize Sensitive Fern) In 2007, I was tromping through a bog in Horry County, SC, and spotted a patch of the deciduous sensitive fern that seemed much larger than the typical size plants that grew nearby. Upon planting a rhizome in our home garden, it didn't let me down, producing leaves much larger than normal. The giant 3' tall fronds (2' tall is normal) are comparable in size to our other giant Onoclea, 'Texas Too Tall'. When the fronds of Onoclea sensibilis 'Supersize' emerge in spring, they also have a nice red central stipe, whose color later fades in the heat. Moist rich soils will produce the largest size plants. Remember that these spread by rhizomes, so don't plant them near other less aggressive plants. (Hardiness Zone 3a-9b)
Onoclea sensibilis ‘Texas Too Tall’ (Texas Too Tall Sensitive Fern) We snagged a piece of this unique sensitive fern from a boggy site in Caddo County, Texas in 2004, because it seemed larger than the norm. In our gardens, Onoclea 'Texas Too Tall' has produced 3.5' tall early-season red-stiped fronds compared to normal 24" fronds, but what else do you expect from Texas? Although moist soils are preferred, sensitive fern is amazingly drought tolerant. Sensitive ferns spread by non-aggressive rhizomes just below the soil surface and will make a 6' wide deer-resistant clump in 5 years. Insulting or otherwise dissing a sensitive fern is considered a hate crime in the blue states, but say what you like in Texas! (Hardiness Zone 3a-9b)
Osmunda japonica (Japanese Royal Fern) There are many plants separated at birth by the giant continental divorce and Osmunda japonica is one of the orphans. In form, it closely resembles our native Osmunda regalis except that the pinnae (fern leaves) are much thicker and more pointed. Additionally, the upright, deciduous fronds rarely exceed 3' tall. Unlike Osmunda regalis whose fronds can be part fertile and part un-fertile, Osmunda japonica chose an either/or option with the fertile frond entirely modified but not appressed as in Cinnamon Fern. Rich, moist soils will produce the largest clumps. (Hardiness Zone 6a-9b, at least)
Osmunda regalis (European Royal Fern) This is the European native counterpart of our native Osmunda spectabilis. In appearance, the plants are quite similar in forming a 3' tall, vase-shaped deciduous clump. In late spring, the clumps are adorned with a spore-filled pinnae atop the fertile fronds. As a rule, Osmunda regalis has more leathery fronds and the pinnae (leaflets) are spaced closer together than in the American form. Moist soils will produce the largest plants, but Osmunda regalis is amazingly drought tolerant. (Hardiness Zone 3a-10b)
Osmunda regalis 'Cristata' (Crested European Royal Fern) The deciduous light green foliage resembles a regular royal fern, except for the ends of the leaves that resemble a three lobed club...probably designed for giving attitude adjustments to nearby misbehaving hostas. In spring, the upright vase shaped clumps are topped with fertile cinnamon spears. (Hardiness Zone 3a-10b)
Osmunda regalis 'Purpurascens' (Purple Stipe European Royal Fern) Royal ferns are truly one the most distinctive and spectacular bold textured deciduous native ferns. The light green leathery leaves give a very tropical appearance. With adequate moisture, these can reach 6' tall by 3' in width. The fertile fronds appear as bronze spears, emerging from the center of the clump in spring. This strain of European Royal Fern has a dark purple stipe/rachis adding to the beauty. (Hardiness Zone 3a-10b)
Osmunda spectabilis (American Royal Fern) is truly one of the most distinctive and spectacular, bold-textured, deciduous native ferns. The light green, leathery leaves give a very tropical appearance. With adequate moisture, American Royal Fern can reach 6' tall by 3' wide, but 3' tall is typical. (Hardiness Zone 3a-10b)
Osmundastrum cinnamomeum var. asiaticum (Asian Cinnamon Fern) This is the Asian version of our native species. It is rarely seen in American gardens but would appear to be just as useful and vigorous. (Hardiness Zone 3a-10b)
Osmundastrum cinnamomeum var. cinnamomeum (American Cinnamon Fern) This deciduous American native is one of our most stately large ferns. The upright clumps thrive in moist soils but also grow well under typical garden conditions. This is a great large foil in woodland settings. The fertile fronds arise in spring just above the sterile foliage as a cinnamon-colored spike in the center of the clump. In moist soils, a happy clump of cinnamon fern can reach 6' tall by 3' wide, although 3’ tall is more typical. (Hardiness Zone 3a-10b)