This section is from the book "The Native Flowers And Ferns Of The United States ", by Thomas Meehan. Also available from Amazon: The Native Flowers and Ferns of the United States in Their Botanical, Horticultural, And Popular Aspects.
Fronds (three to four inches long) lanceolate, pinnatifid, or pinnate below, tapering above into a slender prolongation, " the apex sometimes rooting;" lobes roundish-ovate, obtuse, or the lowest pair long-acuminate; fruit-dots irregular, those next the mid-rib often double, even the slender prolongation fertile. (Gray's Botany of the Northern United States; see also Chapman's Flora of the Southern United States, Eaton's Ferns of North America, Williamson's Ferns of Kentucky, and Wood's Class-Booh of Botany under the name of Antigramma pinnatifida.)
WHILE admiring the rare beauty of this little fern as exhib-ited in our plate the reader may come across Mr. Williamson's remark that "this species is one of the most unattractive of the whole genus," and may pause to inquire whether the first favorable impression be correct. But its true beauty becomes more apparent under a critical examination, and we conclude that Kentucky plants do not grow as pretty as the specimen illustrated, which was taken from the location near Philadelphia where the species was first found. The beauty is of the slender sylph-like type, and yet there is enough of an air of solidity to warrant a more substantial claim. The combination of straight lines with curves is singularly happy; and though the transition from the straight line of the stipe to the curved divisions of the frond is somewhat sudden, this at length gives beauty by the contrast which it makes to the gentle flowing away of the curves into the straight prolongation at the apex. Again, there is real beauty in the gentle passing of the brown into the green at the base of the fronds, while the rich brown color of the fruit dots in small straight lines is in excellent contrast with the green and curved outline of the divisions of the frond. Of course this effect is heightened by the warm color of the withering fronds, but the beauty of the plant is entitled to full credit for this item, for the artist found them there. Further it may be said that the artistic arrangement of the fronds lends the plant much beauty. The curving of the left-hand lower frond with the brown-dotted under-surface of the upper one, nicely balances the upper-curved and brown under one on the right side, and makes a variation in harmony very pleasant to enjoy. But even here it is only because the artist had what nature afforded him. It is the artist's fidelity to nature which makes the picture beautiful. The fronds would furnish valuable material to designers in ornamental work. The lovers of plant-life, as well as lovers of mere beauty, will find much to interest them in this little fern. The first leaves of the spring are very small, and as they appear the last season's fronds begin to die. The earliest leaves are but slightly lobed, merely crenate, as the text-books would say. These nearly entire leaves are barren, but other small fronds soon appear, and more deeply cleft, and others successively enlarge till fronds four or five inches in length are formed. The special interest in this fern is that no sooner do the fronds become deeply lobed but the fruit dots appear, no matter how small or how early produced in the season these fronds may be. As we see in our plate a small frond, not one inch in length, is yet covered by fruit dots. Probably no fern known is so enormously productive of spore cases as this species. Now all these points happen to be in striking contrast with another fern with which it was in its early history associated - the Camptosorus rhizophyllus. Of this one Michaux says, fructificatione inordinate sparsis; that is to say, fruit unusually scarce. And this scarcity of fructification is indeed a well-known character of this, the Walking Fern. Then as regards the lobing, the Walking Fern in its earlier stages has very entire fronds, but as the successive growths increase in size, auricles at the base, and other tendencies to division appear, and it is only as these tendencies develop that the fronds increase in productiveness. Dr. Chapman, in his Flora, notes that he had seen a form in which the two lower lobes had made prolongations horizontally, in this resembling one of the characters of the Walking Fern. The change of form with approaching productiveness is a very common characteristic in plants. Sometimes with entire leaves in the infertile condition, they become divided in the fertile, and sometimes the reverse is the case; but the direction of change is always uniform in allied species. It may be surmised from these considerations that Asplenium pinnatifidiim and Camptosorus rhizo-pliyllus on modern theories of development were originally of one parentage, and that the latter with more fertile tendencies assumed those characters which seem inseparable from the more fertile state. This speculation derives more force from the occasional attempts of each to assume characters usually peculiar in the other. The increased tendency to productiveness as the fronds in the Walking Fern become deeper lobed, has already been noted, as well as the tendency to barrenness in our present species when its fronds are entire. In addition to this it sometimes happens that Asplenium pinnatifidum comes near "walking" by the formation of a prolongation and the appearance of a small swelling at the end. It is generally doubted that it actually roots at the tip; but Mr. Eaton observes that he has seen an enlargement at the apex, as if there were an attempt to form a proliferous bud; and the writer of this once saw a similar case in a plant growing in a green-house, where the prolongation reached over to the ground with the enlargement apparently ready to root, when the frond was accidentally destroyed. Dr. Gray in our description quotes from some source, "the apex sometimes rooting;" and Mr. John Smith in "Historia Filicum" places it in his division of species actually rooting, and speaks of having had the living plant to observe from. Our plant has straight veins, as seen in our enlarged Fig. 2, while the Walking Fern has netted veins; but even these characters in ferns are known to be in intimate relations with fertility. There is therefore no reason that we can draw from analogy against the original identity of parentage of these two very different species; and this consideration gives them an additional interest unusual among plants, wherein grounds for identity of origin often exist without the opportunity for comparison offered here.
The name Asplenium pinnatifidum is usually credited to Nut-tall, who described it under this name in his "Genera" in 1818. But the plant was known to Muhlenberg, the famous Pennsylvania Botanist, who in 1813 included it in his "catalogue" as Asplenium rhizophyllum, variety pinnatifidum; by which we see that the only relationship Nuttall has with its history is the expression of his belief that it was a little more distinct from the Walking Fern than Muhlenberg thought it was.
For a long of time it was believed to be confined to the rocks of which Nuttall speaks, on the Schuylkill near Philadelphia, and a few places in the South. Even so late as 1870, Professor Gray says in his "School Botany," that "it is very rare." But it is probable that Muhlenberg, before Nuttall's time, had specimens from near his own Lancaster home. Professor Porter has found it there, as well as at Christiana, York, and other places in the State of Pennsylvania. The writer of this found it abundantly on rocks at South Pass, Illinois, in 1865; and Mr. Williamson, in the "Ferns of Kentucky," speaks of it as abundant on the sandstone and limestone rocks of that State. It has been singularly overlooked, and the endeavor to find it in other places than those recorded, may give much zest to the fern-lover's explorations.
1. A full-sized plant from a cleft in a rock in Fairmount Park, Philadelphia, collected by Mr. Joseph Meehan.
2. An enlarged pinnule showing the veins and fructification.