Pteris Plant is additionally referred to as the brake, a genus that's on the brink of 280-300 species of ferns widely spread across subtropical and tropical regions. Species of Pteris are often seen on the valleys and roadsides of North-Western and Western Himalayas. The P.cretica can grow up to an altitude of 2400m, P.vittata grows less than 1200 m altitudes. Some of its species found in India are – P.wallichiana, P.stenophylla, P. quadriaurita, P.pellucida, P.critica, P.vittata, etc.
The Life Cycle of Pteris
Pteris is a terrestrial genus that inhabits shady and moist forests and hilly areas. Pteris, the Latin name corresponds to the Greek word for a fern.
In the life cycle of Pteris, the sporophyte is the dominant phase. The sporophyte is the dominant phase which is said to be diploid and independent.
The lifecycle can be differentiated into stem, roots, and leaves. Roots arise from the underside of the Rhizome. It can also be around the surface.
The embryo gives rise to primary roots which have a short life span, they are replaced by the adventitious roots.
Spores are produced in the coenosorus. The spores develop into the prothallus via germination which leads to the gametophyte stage (haploid).
The nature of prothallus is, they are short living, independent, and highly reduced.
As a result, egg and spermatozoids are formed. A diploid zygote is the normal sporophyte formed with the fertilization of the spermatozoa and the egg.
Pteris - Classification
The scientific classification of Pteris is as follows:
Pteris - External Morphology
The underground stem is branched and perennial, rhizomatous, and surrounded by brown scales. A few of the species on their rhizomes have lasting leaf bases.
Leaves arise from the upper portion of the rhizome having an extended rachis. The Petiole base is sometimes covered with ramenta and some other times covered with brown scales.
Leaves are unipinnate compounds, microphyllous, arising in an acropetal pattern on the rhizome. The Bipinnate leaves, digitate and decompound leaves are also observed in some species.
Leaves that are developed are mentioned as fronds. The rachis comprises many sessile, coriaceous, lanceolate leaflets organized in pairs apart from the terminal leaflet.
The leaflets while reaching the apex they eventually narrow down and they are broader towards the base. The leaflets that are found in the middle are large while other leaflets exhibit a gradual decline in size in the apical and basal sections of the rachis.
Leaflets are rough having a midrib, from here lateral veins project with a dichotomous sort of branching. It exhibits an open dichotomous venation. We can find a gradual rate of growth and the younger leaves exhibit circinate vernation.
Pteris - Anatomy
Pteris anatomy includes the following terms:
It is oval and when they are seen through the T.S section we can find cortex, epidermis, and stele.
It's covered with thick cuticles and is single-layered with quadrangular cells.
It's differentiated into four-five layers of sclerenchymatous hypodermis and therefore the inner broad parenchymatous area. These regions possess leaf and root traces.
It varies between species. Meristems are found implanted in the ground tissue. Each of these meristele is a single-layered elliptical where the endodermis comprises Casparian strips inside their radial walls. One-two layered pericycle is found enclosing the phloem under the epidermis. The xylem is located to the meristele, exhibiting central protoxylem encircling either side of the metaxylem. It comprises the xylem parenchyma and tracheids. The Phloem on the opposite side has phloem parenchyma and sieve cells. It surrounds the xylem.
Pteris - Reproduction
Reproduction in Pteris is by means of vegetative and asexual.
Asexual reproduction occurs through the formation of spores. As it produces one sort of spore only, it's homosporous.
Vegetative reproduction occurs by eventual death and decaying of the older sections of the rhizome. The branch and main axis get detached which grows as a new plant.
Pteris is commonly known as the Chinese brake. Pteris grows in the wild. As it is very attractive it is also grown in gardens, on concrete structures and cracks, and on the buildings, it is also used in the pollution control schemes. It helps in the absorption of a highly toxic element called arsenic, and stores it in the fronds of it without drying out.