Rickettsias are mainly known for their disease-causing capability. These micro-organisms can cause a great variety of diseases in different flora and fauna; especially in human. Rickettsiosis is a disease caused by intracellular bacteria. It’s a type of infectious disease. Rickettsiosis can be divided mainly in two groups: Spotted fever group …

Systematic Position Division: Lycophyta / Lepidophyta Class: Eligulopsida Order: Lycopodiales Family: Lycopodiaceae Genus: Lycopodium Also known as club mosses, Lycopods, creeping pines or tailing pines. Ligule: A membranous outgrowth projecting from the leaf sheath. On the basis of ligule, Lycophyta has 2 classes: Eligulopsida: Lycopodium phylloglossum Liqulopsida – Isoetales, Selaginellales …

Psilotum is commonly known as Whisk-fern. Salient features of Pilotum The sporophytes are dichotomously branched with an underground rhizome and upright branches. The upright branches are leafless. Rhizoids are present instead of root. Stem has a relatively simple vascular cylinder. The sporangia are born in groups (trilocular) and form synangia. …

A stele is the central cylinder or core of vascular tissue in higher plants and Pteridophytes. It consists of the xylem, phloem, pericycle, medullary rays, and pith if present. The term stele has been derived from a Greek word meaning rod or column. Van Tieghem and Douliot (1886) introduced this …

The word cryptogams is a synthesis of two Greek terms kruptos meaning ‘hidden’ and gamos meaning ‘wedded’. This single term encompasses all plants that reproduce by means of spores and, do not produce seeds. The algae, fungi, bryophytes and pteridophytes are all cryptogams. The pteridophyta are treated as vascular cryptogams …

The term Pteridophyta was first coined by Haeckel. Eichler (1883) divided the plant kingdom into Cryptogamia and Phanerogamia. The Cryptogamia was further divided into Thallophyta. Bryophyta and Pteridophyta. Engler (1909) included the Bryophyta and Pteridophyta under Embryophyta. Due to discovery of the fossil plants, the classification of Pteridophytes has undergone …

They are the earliest known vascular plants that originated in the Silurian period (400 million years ago) of the Palaeozoic Era and subsequently diversified and formed the dominant vegetation on earth during Devonian to Permian period. There are controversies regard­ing their origin and evolution. There are two broad theories about …

Telome theory was proposed by Walter Zimmerman (1952, 1965). This theory is based on fossil records and explains the major steps in the evolution of vascular plants. According to this theory, all vascular plants have evolved from simple, leaf-less, root-less and dichotomously branched sterile and fertile axes called telomes which …

In the kingdom Fungi, there are two major phyla- Ascomycota and Basidiomycota. These two together form a subkingdom of fungi named as Dikarya. They together were named such as members of both phyla maintain most part of their life cycle in dikaryotic stage meaning each cell contains two genetically different …

Modern embryology seems to comprise three main disciplines. The first, or descriptive embryology, is a study of the various developmental processes that take place in a plant from the initiation of the sex organs to the maturation of the embryo. The second, or phylogenetic embryology, attempts to evaluate these data …