Evergreen Wood Fern -BOG

Evergreen Wood Fern /D. intermedia

Order:Polypodiales Family:Dryopteridaceae Genus:Dryopteris


General Characteristics:
-A large, lacy, woodland fern; identifiable by its larger size, thrice-cut fronds. Petiole (leaf stalk) 1/3 length of leaf, scaly at least at base; scales scattered, brown with dark brown stripe.
-Blade green, deltate-ovate, thrice-cut and lacy. Pinnae (primary leaflets) more-or-less in plane of blade, lanceolate-oblong; basal pinnae triangular and slightly reduced in size.
-Rootstalk erect or ascending, producing offshoots.
-Sori midway between midvein and margin of segments.

special adaptations:
Each sorus consists of clusters of spore cases called sporangia that are shielded by a flap structure called an indusium. The asexual spores are released according to environmental conditions to enhance survival. Spores that land in favorable growing areas develop into an intermediate sexual structures called prothallia, which subsequently produce male and female organs known respectively as the sperm producing antherium and the egg bearing archegonium (in most cases on the same prothallium). The preference of ferns for boggy areas is due to the need for a film of moisture so that the sperm can swim to the eggs. The motile sperm is believed to be due to the retention of the processes of their aquatic ancestors. The fern frond grows from the resultant zygote.