About Dryopteris intermedia subsp. azorica (Christ) Jermy
Dryopteris intermedia is a perennial fern that grows 40–90 cm tall and 60–90 cm wide. It has an underground rhizome at its base, from which fronds grow in a spiral arrangement. Each frond has a stipe (stalk): the base of the stipe is covered in light-brown scales, and the upper section of the stipe is covered in short glandular hairs. Stipes are generally 1/4 to 1/3 the total length of the frond, and each stipe supports a lance-oblong shaped leaf blade. The leaves are bipinnately compound, meaning they divide into primary leaflets called pinnae, which further divide into smaller sub-leaflets called pinnules. The pinnules of this fern are lobed and toothed. A distinctive identifying feature is that the first pinnule closest to the main stem on the lowest pinna is shorter than the second pinnule. Similar ferns growing in the Azores are often classified as the subspecies Dryopteris intermedia subsp. azorica, or alternatively classified as a separate species, Dryopteris azorica. This species is native to most of eastern North America. Its range extends from Minnesota in the northwest, and Newfoundland and Labrador in the northeast, south to Alabama in the southwest and South Carolina in the southeast. Globally the species is secure, but according to NatureServe, it is listed as critically imperiled in the U.S. states of Iowa and Missouri, which mark the western edge of its native range. It is listed as imperiled in the U.S. states of Illinois and South Carolina, and the Canadian region of Labrador. Dryopteris intermedia grows in a wide range of mesic habitats, including forests, woodlands, ravines, swamp edges and rocky slopes. In North America, this fern is cultivated as an ornamental plant for gardens, particularly natural gardens and shade gardens. It is valued for cultivation because it grows easily in a range of environments and soils, and does not spread aggressively. When planting, care must be taken to place this fern in a site with part shade or full shade and keep the soil consistently moist, as it cannot tolerate prolonged full sun or dry soil.
