1. Thallus: Fern prothallus is a gametophytic plant. Its body cannot be divided into roots, stems and leaves. That is, they are thallus shaped. The thallus is green, flattened, hemispherical, flattened, multicellular and cordate. It has a large groove at its tip. This is called the anterior notch. Prothallus being green can produce food through photosynthesis.
2. Rhizoids: Slender, linear, unbranched, colorless and unicellular rhizoids arise from the lower surface of the thallus. Rhizoids are of two types. Smooth and rough rhizoids. Rhizoids anchor the thallus to soil or other material and absorb water and mineral salts.
3. Scales: Thin, filiform, unbranched, colorless and multicellular scales arise from the lower part of the thallus. It attaches the thallus to the soil or other material and absorbs water and mineral salts. Scales protect the thallus from desiccation in unfavorable environments.
4. Genitalia: Pteris is a companion plant. Their male and female genitalia are located in the same thallus. Its male genitalia is called antheridium and female genitalia is called archegonium.
(i) Antheridium: On the underside of the thallus several spherical or ovoid stamens antheridia grow. At its base are two ring cells and a lid cell. Inside the antheridium are 20-50 sperm mother cells or androcytes. Each spermatozoon matures into a multi-flagellated spermatozoon.
(ii) Archegonium: Under the anterior groove several female archegonia of pitcher or flax shape are produced. It consists of two parts. Neck and Abdomen. The neck is slightly curved and composed of few neck duct cells. Abdomen contains an ovary and an abdominal duct cell. The cervical duct cells and ventral duct cells of the mature archegonium fuse to form a duct. The alimentary canal is filled with mucilage and malic acid.