Dryopteris or the male fern or wood ferns is a fern genus belonging to the family of Dryopteridaceae. It is a genus of nearly 250 species of ferns. They are found inhabiting the temperate Northern Hemisphere with the most species diversity seen in Eastern Asia. A majority of the species possess stout, slowly creeping rootstocks forming a crown consisting of a ring of fronds resembling a vase-shape. They have a round sori with a peltate indusium wherein the stripes possess salient scales.
Dryopteris comprises horizontal roots that thrive in soil referred to as rhizome, their leaves project upwards and are known as fronds. Each of this frond is somewhat triangular in shape with its branches on either side of a stem with several small oblong leaflets. The frond spouts are referred to as fiddle heads as they resemble the head of a violin.
Dryopteris – Structure
The plant body of the sporophyte can be divided into roots, leaves and the stem (rhizomatous).
They possess branched and small roots. They have an ephemeral primary root substituted by many adventitious roots emerging from the bases of the leaves. Their outer layer has a central stele and a cortex wherein they can be distinguished into an inner sclerenchymatous and outer parenchymatous zone. Steles are diarch xylem and protostelic with exarch.
They have a rhizomatous stem partially erect and partially horizontal where the apex projects above the surface of the soil. They possess scales with adventitious roots. The rhizome anatomically exhibits an outer one-layered epidermis a parenchymatous cortex (broad) having a centrally oriented dictyostelium vascular bundles enabled with several meristeles and some layered thick brown sclerenchymatous hypodermis.
The meristeles are oriented in the form of rings, with leaf gaps. Each of the meristele is elliptical or round where the mesarch xylem is engirdled by phloem. Stele is bound by endodermis of 2 layers where the exterior layer is distinguishable and the interior layer unites with the pericycle of 1-2 layers. A few vessels and Tracheids constitute xylem produced due to dissolution of the end walls of the tracheids.
Acropetal leaves are found at rhizome’s apex. The leaves seem to be coiled spirally when they are young and display circinate ptyxis which are ideally seen in true ferns. Fronds are uni-pinnately compound having a long rachis. When the old leaves wither away the leaf bases still persist.
Fertile leaves are seen having sori on the abaxial pinnae surface. The rachis’ base is covered by brown scales known as ramenta.
Production of spores
The life cycle of ferns commences with the spore. Each frond on its underside has dark and tiny spots known as sori which have sporangia – growths producing and releasing spores.
Each of the spores falls to the ground ultimately. The spores which germinate, go on to form the gametophyte which in turn grow forming a leaf-like structure attaching to the ground through rhizoids.
On maturity, the gametophyte gives rise to the sex structures wherein the male organs are referred to as the antheridia and the female structures are referred to as the archegonia. Both these structures take form on the base of the gametophyte.
Reproduction through sexual means
The male structures, antheridia produce flagellated sperms which swim across the film of the water to reach the archegonia. Then the sperm goes into fertilizing the egg present in each of the archegonium.
The process of fertilization produces zygote growing from the inside of the gametophyte. The rhizomes grow underneath the soil while the fiddleheads sprout, projecting from the rhizome forming sporophytes.
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