Aspleniums offer a wonderful assortment of fascinating and decorative ferns ranging from elfin and temperamental miniatures to willing rock plants and finally to mammoth tropicals that perch in treetops and adorn living rooms. The name is
derived from the Greek a, without, and splen, spleen, and was named by Pliny and Dioscorides, the father of pharmacy, around a.d. 60 because of the fern's reputed ability to cure disorders of the spleen and liver. (Boil the "leaves" in wine and drink for 40 days was Dioscorides' recommendation.) There are approximately 700 species and more than 100 hybrids in this sprawling genus. They are largely denizens of tropical comforts. The temperate species, by contrast, prefer challenging rocky substrates, cliff faces, and associated inhospitable and frequently inaccessible sites.
Many authors include Camptosorus, Ceterach, Phyllitis, and Schaffneria in the Asplenium classification due to the ability of these genera to interbreed. However, there are botanical differences that can warrant maintaining them as separate genera. I follow the lead here of popular works by Chris Page (1982), John Mickel (1994), and Barbara Hoshizaki and Robbin Moran (2001).
The usually erect rhizomes of this genus have unique translucent clathrate (latticelike) scales. The stipes of varying heights are dark or may be a rather peculiar two-toned combination of dark on the outer side and green inward. This contrasting feature frequently continues up into the rachis. Characteristic back-to-back C-shaped vascular bundles merge into an X in the frond's upper portions. Blades are evergreen and range from simple to finely dissected tripinnate to quadri-pinnate laciness. Distinctive sori are linear and arranged in a herringbone fashion along veins. A single indusial flap of tissue opens in the direction of the pinna midrib (thus differentiating this genus from Phyllitis with its two-sided double opening sori). The veins are free.
Most temperate species tend to be alpines that cling tenaciously to their preferred rock strata and adjust reluctantly to an exiled life away from such habitats. It can be done, however, with geological wisdom tempered by a great deal of patience and testing (of both the fern and grower). While some specimens are willing in cultivation, others are difficult, and still others are very difficult and downright ungrateful. Customized container culture offers the best promise for initial trials. With many of the alpine- and rock garden-inclined species being dwarf at maturity, containers offer the added advantage of revisiting details in "up close and personal" viewing, portability to find the ideal site, and a measure of isolation from the ever-present threatening army of slugs. Regardless of the selected planting site, Asplenium crowns with their "delicate constitution" should be protected from rain or sprinkler-induced splattering soil. A top dressing of moss or pebbles and, in specific instances, limestone chips serves admirably to deflect superfluous moisture and give the planting a tidy presentation. (This is true with all dwarf ferns.)
Many of these species are lime lovers, but I have had disastrous results when adding lime especially that which is traditionally used to sweeten lawns. Gypsum, though periodically recommended, has been deadly. What is needed is a handy limestone quarry as a source for rocks and chips. Barring that, I add eggshells, which may or may not help the ferns, but at least makes me feel as if I am being accommodating. I have also had success by lining the larger species along the concrete foundation of the house and/or adding chunks of broken concrete to the planting hole.
The tropical species, primarily for indoor use, like good humidity, small pots, filtered light, and minimal watering. More indoor fern furnishings are lost to drowning than they are to drought.
Aspleniums rarely produce offshoots for division. They compensate by coming readily and rapidly from spores. I sow mine on my traditional earthworm compost mix and, when transplanting, I add grit.
Historically, aspleniums have contributed to concoctions of herbal cures. In addition to healing the spleen, they have been used as a poultice for wounds, tea tonic for curing baldness, and even as a salve for broken limbs.
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