|Nephrolepis exaltata subsp. var.||Sword fern, Boston fern|
The Sword Fern (Nephrolepis exaltata) is a species of fern in the family Lomariopsidaceae (sometimes treated in the families Davalliaceae or Oleandraceae, or in its own family, Nephrolepidaceae), native to tropical regions throughout the world. It is common in humid forests and swamps, especially in northern South America, Mexico, Central America, Florida, the West Indies, Polynesia and Africa. Also known as the Wild Boston fern, Tuber ladder fern or Fishbone fern is in the broader family of sword fern.
The fronds are 50-250 cm long and 6-15 cm broad, with alternate pinnae (the small "leaflets" on either side of the midrib), each pinna being 2-8 cm long. The pinnae are generally deltoid, as seen in the picture to the right. The pinnate vein pattern is also visible on these highly compound leaves. The edges appear slightly serrate. The species has erect fronds, but Nephrolepis exaltata cv. Bostoniensis (Boston Fern), the most commonly cultivated cultivar, has gracefully arching fronds. This mutation was discovered in a shipment of N. exaltata to Boston from Philadelphia in 1894.
|Standard Cyclopedia of Horticulture|
Nephrolepis exaltata, Schott. Sword-fern. Lvs. rather rigid and erect, 2-5 ft. long, 3-6 in. wide, oblong, tapering toward the point, the pinnae rather close, acute, entire or crenulate, the upper side auricled. Fla. to Brazil, Hong-Kong and E. Afr.—This description applies only to the wild species. It is impossible to give a description which will include all the forms which have been derived from this species. Each distinct form needs separate treatment. The varieties of N. exaltata have practically all arisen in the last twenty years, since the early nineties. At that time this species was grown to some extent by florists as a house-plant but was not more common than many flowering species. It happened, however, that in a lot of this species of about 200 plants, shipped by Robt. Craig & Co., of Philadelphia, to F. C. Becker of Cambridge, Mass., there was discovered one plant which differed from the ordinary exaltata in being more graceful, slightly broader, and a quicker grower. The purchaser identified this plant as the species acuminata or, as it was then called, davallioides, and proceeded to raise and sell it by the scores of thousands. Later, when a specimen of the fern came into the hands of G. W. Oliver, the latter raised the question of its identification and declared that it was not davallioides but exaltata, though not the typical form. For some time thereafter Messrs. Becker and Oliver exchanged opinions in the "Florists' Exchange," until Oliver's determination was accepted. The nomenclature commission of The Society of American Florists did not feel competent to give a name to the new variety so it was sent to Kew where it was suggested that the neighborhood of its discovery might well be honored by calling it bostoniensis. This name was given in 1896. The fern had been on the market for a year or more previously.
For nearly ten years the Boston fern held undisputed sway. The original species-form was superseded owing to its less graceful stiffer habit. Then in 1903 there appeared a new type of variation in the greenhouses of F. R. Pierson, of Tarrytown, N. Y.
In this new form, the Boston fern departed from its once-pinnate type to give rise to a twice-pinnate form which was introduced as Piersonii. But this fern was not consistently once or twice pinnate but both, and after a time it appeared that this unstable condition was not very satisfactory. It was found possible to obtain by careful selection a more fixed type of the twice-pinnate form and when this was introduced it was given the name of elegantissima. This was followed by other forms showing the two-pinnate character, and later forms appeared three and even four times divided.
A year or two later, in Brooklyn, another type of variation developed from the Boston fern. This was the dwarf type, with which came some other differences, but with the once-pinnate character retained as in the parent form. John Scott brought out the first of these dwarf types but there are now a half-dozen different dwarf once-pinnate forms.
About this time Harris, of Philadelphia, discovered and introduced a once-pinnate type with beautifully waved pinnae and called it Harrisii. This has since been followed by wavy dwarfs, wavy twice-pinnate forms. Pierson again came to the front with a new type of variation in which the leaves are irregularly curled and twisted so that the resulting leaf becomes a dense thick mass of divided pinnae, the superbissima and muscosa forms.
At the present time, with these four main types of variation to start with, and with others, such as thickness of petiole, rapidity of growth, stability of form, and the like, there have come almost all possible combinations and mixtures of these main types so that within certain limits almost anything is possible. Every grower who produces any quantity of these forms is having new types develop in his beds. Many of these are of no commercial value. A few new ones are introduced each year but some which at first appear good prove to have serious defects after testing for a year or two.
It is an interesting fact that, after ten years of new forms, the old Boston fern still holds its own and sells more readily and in larger amounts than any new form. It appears that with the later variations there has come also less adaptability to house conditions and more or less decrease in the vigor of growth.
While these variations have been appearing in American greenhouses, the same thing has been taking place in Europe. In some cases the new forms produced and named are practically identical on both sides of the Atlantic, but each region has produced distinct types not yet developed by the other. Generally speaking, there has been almost no importation into North America of the new European forms. For this reason little attention is here paid to European forms in this treatment. Not much is known about them by our growers and collectors.
The classification of the forms of N. exaltata is a difficult problem on many accounts. In the first place, owing to unscientific horticultural methods of description and publication of names, it is practically impossible to get accurate printed records of the different forms. Some growers have the custom of merely placing a new form on the market without so much as a catalogue or periodical advertisement. At best it is a case of advertising descriptions for the purpose of sale so that what is stated can not be accepted for the purposes of close and accurate description. In the second place, the types of the variations themselves are often of such a character that it is hard to draw up good differential descriptions. Two varieties may vary not at all in the cutting of the leaves but very markedly in the important characters of cultural needs and response. Again, it is usually the case that earlier varieties become superseded by later ones of greater commercial possibilities. The grower then has no sentiment about the original forms but discards them, so that it is practically impossible now to get plants of some of the early stem varieties from which nearly all of the later have sprung. Added to these difficulties is often indifference on the part of growers to the need of accuracy in naming forms. A single form may be sold by different florists under totally different names.
The descriptions given below of the various forms have been drawn up as far as possible from authentic material obtained from the original producers themselves. Numerous visits have been made to growers in the neighborhood of New York, Boston, and Philadelphia. A collection of living plants has been started at the Brooklyn Botanic Garden, the main object of which is to gather authentic plants of the varieties. It should be noted here that, however careless as to the accuracy of descriptions and names the various growers have been, they have been exceedingly courteous in affording opportunities for study and in giving such information as they possessed.
The varieties chosen for description are those found to be in actual cultivation for the trade in the United States, together with some formerly in the trade but important because the modern varieties have sprung from them. Whenever possible, other varieties have been given incidental description by comparison with the more important forms. In some cases it has not been possible to settle the claims advanced for two or more similar varieties and in such cases the varieties have been given coordinate treatment with a single description. English varieties about which little information has been available have been mentioned where possible in connection with similar American forms.
In the key below dimensions given are for well- grown plants in 6-inch pots. In the smaller varieties, these dimensions are maximum, but some of the larger types may develop leaves as long as 6 feet.
The Boston fern is a very popular house plant, often grown in hanging baskets or similar conditions. It is a perennial plant hardy in USDA plant hardiness zones 9-11. Although the fern may appear totally dead due to frost, it will re-emerge in the spring. In general, the Boston fern likes damp, but not soggy soil that is rich in nutrients. Of the common cultivated ferns, the Boston fern is the most tolerant to drought. The fern thrives best in humid conditions, so when grown as a house plant it becomes necessary to mist the plant when relative humidity falls below around 80%. Although outdoors this plant prefers partial shade or full shade, inside it grows best in bright filtered light.
Boston fern is native to Florida, the West Indies, and Asian Pacific. A related species, the Tuberous Sword fern (Nephrolepis cordifolia), is frequently confused with Boston fern and is a serious exotic invasive plant, forming dense monocultures. </center>
This plant is usually propagated by division of the rooted runners, as named cultivars will not produce true spores.
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- Wild Boston fern.jpg
Wild Boston fern
- Wild Boston fern02.jpg
Wild Boston fern
- Standard Cyclopedia of Horticulture, by L. H. Bailey, MacMillan Co., 1963
- w:Nephrolepis exaltata. Some of the material on this page may be from Wikipedia, under the Creative Commons license.
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