What is Riccia thallus?
Riccia is a genus of liverworts in the order Marchantiales. These plants are small and thalloid, that is not differentiated into root, stem and leaf. The thallus is dorsiventrally differentiated. Its upper (dorsal) surface is green and chlorophyll-bearing, with a mid-dorsal longitudinal sulcus (furrow or groove).
What branching is Riccia thallus?
The thallus in Riccia is dichotomously branched and the growing point is situated in its apical notch.
What is thallus in bryophytes?
The mature gametophyte of most mosses is leafy in appearance, but some liverworts and hornworts have a flattened gametophyte, called a thallus. The thallus tends to be ribbonlike in form and is often compressed against the substratum to which it is generally attached by threadlike structures called rhizoids.
Which region of the thallus of Riccia which stores water and reserve food material?
It is dichotomously branched (Fig. 152) and green to light green in colour. 3. Thallus is thick in the middle and becomes thin towards the margins.
What is the habitat of Riccia thallus?
3.1 Distribution and Habitat Most of the species of Riccia are terrestrial while few are aquatic in nature. The terrestrial species grow on clayed damp soil or tree trunks or wet walls while aquatic species occurs as free floating or submerged in pools, ponds or lakes.
How do Riccia reproduce?
The reproduction in Riccia takes place by means of (1) vegetative and (2) sexual methods. Vegetative Reproduction, By the death and decay of the older parts of the thallus, By adventitious branches, By cell division or gemma formation, By tubers, By thick apices.
What is the structure of Riccia?
The gametophytic plant body of Riccia is a dichotomously branched dorsiventral prostrate thallus. In terrestrial habits, the plants usually occur in a rosette form due to the presence of a number of dichotomies that grow together from one place (Fig. 6.1 A-C). These rosettes are up to 15 cm in diameter.
What is thallus like structure?
A thallus is composed of filaments or plates of cells and ranges in size from a unicellular structure to a complex treelike form. It has a simple structure that lacks specialized tissues typical of higher plants, such as a stem, leaves, and conducting tissue.
Do mosses have thallus?
The gametophyte thallus of a moss plant is composed of an erect to prostrate “stem” bearing spirally arranged “leaves”. Though morphologically similar in external appearance, these structures ARE NOT the same as the highly differentiated true leaves and stems of vascular plants.
What is Riccia sporophyte?
The riccia sporophyte consists of a peripheral layer of cells that form the wall of the capsule and a central mass of the mother cell that contains spores. The diploid zygote is the first generation of sporophyte cells. The upper cell is called the epibasal cell, and the lower cell is called the parabasal cell.
Where is riccia found?
Species Overview Riccia fluitans is the only truly aquatic liverwort in Florida. Plants have been collected from scattered locales in the northern, central, and southern regions. Unlike most other liverworts, it floats freely in tangled clumps or mats below the water surface.
How do riccia reproduce?
What are the characteristics of Riccia thallus?
Riccia thallus grow in large number in close association, covering the surface like a mat. They are relatively poorly adapted to life on land. So they are mainly confined to damp and shady places. The species of Riccia are terrestrial, nonvascular plants commonly called amphibians of plant kingdom.
What is the external structure of Riccia?
1. External structure:- The plant body of Riccia is flat, dorsiventral thallus, which is prostrate, ribbon like and more or less fleshy. The branching of the thallus is dichotomous. Due to repeated dichotomy and also due to the occurrence of a number of such dichotomously branched plants together at a place, the plants often take a rosette form.
What is thallus 1 1?
1. It is situated on the upper or dorsal surface of the thallus and consists of loose green tissue. It is also known as assimilatory region. 2. It consists of a layer of epidermis, many air pores, air spaces or air chambers and many one-celled thick vertical rows of chlorophyll-containing cells.
What is the difference between Riccia cruciata and are fluitans?
In Riccia cruciata only two dichotomy result in a cruciate form (Fig. 4). Each branch of the thallus is linear, wedge-shaped or obcordate. Thallus is 5-7 mm long and 1.2 mm broad in all the terrestrial species. However, in R. fluitans it is 30-50 mm long and 1-2 mm broad.