This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Tufted evergreen Ferns with pinnate fronds, globose sori, and a peltate orbicular indusium. Upwards of fifty species are described, dispersed nearly all over the world. The name is derived from a shield, the form of the indusium.
1. A. aculeatum, syn. Polystichum aculeatum. - This is one of our commonest hedgerow Ferns, and one of the best for general planting. It has large lanceolate bi- or tri-pinnate fronds, of which the stipes and rachis are more or less clothed with ferruginous scales. The pinnules are obliquely rhomboid, auricled and mucronate or awned, and the sori are arranged in a single row on each side of the midrib. There are three tolerably distinct forms : - A. lobatum, with bi pinnate fronds and rigid sessile decurrent pinnules, confluent below; the variety lonchitidoldes is still narrower, approaching Lonchitis; A. aculeatum proper has larger looser fronds with free sessile pinnules furnished with spinulose teeth; and A. angulare is somewhat membranous with small stalked loose pinnules having bristly teeth. This species is found in .Europe, Western Asia, North America, and the south temperate regions,
2. A. Lonchitis. - The fronds of this species are linear-oblong and simply pinnate, with obliquely falcate spinulose pinnules; and the sori are arranged in two or three rows on each side of the midrib.
Aspidium falcatum, syn, Cyrtomium falcatum, is a very distinct hardy Fern, from China, Japan, etc., with simply pinnate rigid coriaceous shining fronds and large obliquely ovate-acuminate pinnules and numerous scattered sori. A. caryotideum is a variety with larger pinnules, opaque above, A. Fortiinei, syn. A, anamophyllum, has narrower, more numerous opaque pinnules and shorter stipes.