This section is from the book "The Florists' Manual", by William Scott. Also available from Amazon: The Florist's Manual.
The plant in question has been found in fern collections for many years past, and has produced an occasional variation in form from time to time, though it is not a notably prolific species, perhaps the best of these variations from the type being that known as A. tetraphyllum gracile, in which the pinnae are rather narrower than those of the original species and the young fronds show a higher coloring than is found on the type.
A. tetraphyllum may be classed as a moderate grower, the fronds reaching a height of twelve to fifteen inches, and are usually four times divided, or rather divided into four segments. While unfolding the young fronds are frequently bright pink, this color gradually fading as the frond develops, until the mature leaf becomes dark green.
This species prefers warm house treatment, is evergreen, and grows best in a rather loose and open compost. It requires plenty of water at the root, but during the winter especially should not be watered overhead frequently, or the fronds are liable to become rusty. Snails seem to have a special liking for the young foliage of A. tetraphyllum, and close watching is required to get the best of these pests.
A. Wiegandii. A few years since a much greater variety of ferns seemed to be grown for florists' use than is now found among the large trade growers. It is evidently a case of the survival of the fittest, or rather of the species and varieties that may be produced in large quantities with a minimum expenditure of time and labor. Adiantum Wiegandii is one of those varieties that have almost disappeared within a few years, though it is not a particularly tender fern, or one that is difficult to reproduce.
We mention it as a variety rather than a species, because it seems probable that this fern is a form of Adiantum Capillus-Veneris, or else a cross between that species and A. cuneatum, its origin being somewhat obscure. But be this as it may, the fern in question is a very attractive plant of dwarf and sturdy growth, the fronds being almost upright, having black stems and rather large pinnae that are inclined to be cristate.
A. Wiegandii is compact in habit and in a large plant reaches a height of twelve to fifteen inches, and holds its foliage in good condition during the winter. This fern comes freely from spores, the latter being plentifully borne by plants a year old and upwards, and the seedlings soon become satisfactory plants in 3-inch pots if treated in the same manner as A. cuneatum, a night temperature of 60 degrees being a proper mark at which to carry these ferns.
But little trouble is experienced from the damping of the foliage with A. Wiegandii during the winter, even when grown quite close together, the regular use of the hose having less effect upon this fern than is often found with adian-tums of low and compact habit. Thoroughly matured fronds stand well when cut, and the small plants will last longer than those of A. cuneatum in a fern pan, providing they are not used in too soft a condition.
In addition to the fine species described above and many others, all of which make fine specimen plants, the valuable, in fact indispensable, adian-tiun is the cuneatum type, so generally known as the maidenhair fern. Of these the best known is A. cuneatum. Within a few years another species or variety has appeared which originated with Mr. Crowe, of Utica, now sold under the name of A. Croweanum. Some experts have pronounced this a variety of cuneatum, yet there is specific difference, for cuneatum is one of the most prolific with fertile spores, while Croweanum is always sterile and can only be-increased by divisions of older plants. It has also longer stems and larger fronds than cuneatum. O'Brianii is another species, resembling Capillus-Veneris but not as graceful or useful as cuneatum, yet useful to those who do not succeed with the latter, of very free and strong growth. It must be very noticeable to all travelers in the British Isles that A. cuneatum grows with great luxuriance there and under conditions that it does not thrive in here, which simply means it likes the more humid atmosphere found there.
Some years ago A. cuneatum was grown almost entirely in pots. It is now, wherever largely grown for cutting, planted out on benches in five or six inches of good soil. These same cultural directions will also apply to A. Croweanum. Many growers have recommended for soil a fibrous loam, peat and leaf-mold. The finest bench of Croweanum we ever saw growing was planted in a rather heavy turfy loam and cow manure, in fact, an ideal rose soil. It was on a middle bench with very little heat beneath the bench and this I think a valuable point. Ferns don't want bottom heat, it is quite contrary to their natural environments. Shaded from the bright summer suns, a brisk atmospheric heat of 65 degrees is all they need, with liquid manure frequently applied as soon as roots have well spread through the soil. Air-slaked lime was copiously scattered over fronds and crowns of plants and the successful grower remarked that the lime not only kept down slugs and snails, but was he believed a stimulant to the plants, and that I believe we proved is ad there is in growing cuneatum or Croweanum.