Ferns which are great favorites for cultivation out of doors and under glass. The cultivated hardy kinds are natives of North America, the others grow wild in tropical Africa, India and other countries. They belong to the Polypody family, Polypodiaceae. Asplenium is derived from a, not, and splen, spleen, and refers to the medicinal properties these Ferns were said to possess.
The Hardy Kinds. Many of the hardy Ferns previously included in this genus are now referred to Athyrium. Among those which remain are A. platyneuron, the Ebony Spleenwort; A. viride, the Green Spleenwort; A. Bradleyi; and the Maidenhair Spleenwort, A. Trichomanes. They are mostly small Ferns of tufted growth, best suited to planting in shady crevices in the rock garden, in rock walls, and in wild gardens. All, except A. Bradleyi, need a limey soil. For all, the soil should be well drained and not too rich. Planting may be done in fall or spring and they can be increased by division.
For the Greenhouse. The greenhouse kinds differ very much in shape, size and form of the fronds. In some the fronds are entire (undivided), as in A. Nidus, the Bird’s-Nest Fern, while in others, such as A. bulbiferum, they are finely divided. Except that some kinds need a higher temperature than others, the treatment is the same. Propagation is by spores and division and, in the case of A. bulbiferum, by plantlets that form on the leaves.
Suitable Compost. As soon as new growth commences in spring, the plants should be repotted if necessary, in slightly larger pots. Those that are not pot-bound (which have not filled the pots with roots) can remain undisturbed for another year. The best compost consists of equal parts of loam, peat, and leaf mold, with sand added freely. Shade from strong sunlight is essential and the atmosphere must be kept moist by damping the floor and benches.
The chief cool greenhouse kinds are Asplenium bulbiferum, A. Colensoi and A. dimorphum. These need a minimum winter temperature of 50 degrees. The best tropical greenhouse kinds are Asplenium Nidus, A. alatum, and A. cicutarium. They need a minimum winter temperature of 60 degrees. All these greenhouse kinds are satisfactory as house plants, provided the atmosphere is not too dry. Their soil should never be permitted to become dry.