What are the characteristics of Selaginella?
Features of Selaginella (With Diagram)
- Plant body is sporophytic and the sporophyte is evergreen and perennial.
- Most of the species are prostrate but Selaginella trachyphylla is sub-erect and S.
- Size of the sporophyte ranges from few centimetres to several feet in different species.
What is the shape of gametophyte of Selaginella plant?
Structure of the Microspore and Development of the Male Gametophyte: The microspores are very minute in size and range in diameter from 0.015 to 0.05 mm. Soon after separation from the tetrad they will be triradiate but gradually assume a sub-spherical shape.
Is Selaginella Monoecious or dioecious?
The gametophytes produced in Selaginella are heterozygous containing microspores and megaspores as male and female gametophytes respectively. Thus, Selaginella produces dioecious gametophytes. So, the correct answer is ‘Dioecious’.
What is the morphological nature of Rhizophore of Selaginella?
Explanation: The morphological nature of rhizophore of selaginella is unusual. It is considered a root and stem both. Bower & Gobel considered it a structure intermediate between the root and stem, various theories are given to prove this thing.
What is the structure of Selaginella?
Selaginella produces two types of spores—megaspores and microspores. The dimorphic condition of the spores is known as heterospory. In between the sporophyll and sporangium is present a small membranous structure known as ligule i.e., the sporophyll is similar to a vegetative leaf.
What is the evolutionary important character of Selaginella?
Evolutionary important character of Selaginella is heterosporous nature. Selaginella produces two types of spores microspores and megaspores. Heterospory in the life cycle of Selaginella leads to the formation of seed habit.
What is the gametophyte of Selaginella?
The sperms of Selaginella are the smallest among vascular plants. Since the whole process of development of male gametophyte takes place inside the microspore wall, the development is endosporic (where gametophyte develops inside the spore wall) and the gametophyte is an extremely reduced structure.
What is the phylum of Selaginella?
Vascular plant
Selaginella/Phylum
Is selaginella heterosporous or Homosporous?
Lycopodium is homosporous–all spores are roughly equal in size. Selaginella and Isoetes are heterosporous–spores are of two distinct sizes, microspores and megaspores.
Are marchantia monoecious or dioecious?
The liverwort Marchantia is strictly dioecious. Noll showed in 1907 that the spores consist of two classes, those which grow into male plants and those which grow into female plants. Both types of spores are produced in the same sporangium.
What is Homeophyllum and Heterophyllum?
Homeophyllum include species with erect stem and spirally arranged leaves. (Example: S. upestris and S. oregana). Heterophyllum include species with prosrate stem with short erect branches and dimorphic leaves (Example: S.
What is the function of Rhizophore?
It rapidly elongates into a root-like organ which grows downward to the soil, on reaching which, or slightly before, it emits roots close behind its apex which serve to fix the plant in the substratum. The rhizophore usually dichotomizes before reaching the soil.
What kind of gametophytes does the Selaginella produce?
Thus, each microsporangium contains numerous microspores. Selaginella is heterosporous, hence it produces two types of gametophytes, viz., microgametophyte i.e., male gametophyte from microspore and megagametophyte i.e., female gametophyte from megaspore. Thus gametophytes are dioecious (heterothallic). 1.
Which is the only genus in the Selaginellaceae?
Selaginella sp. is a sole genus of vascular plant under family Selaginellaceae and order Selaginellales. The member of this order have herbaceous stems that are usually without any indication of a secondary thickening. Commonly known as spike mosses. Selaginella m os tly occurs in tropical region. It is worldwide in distribution.
How is the plant body of Selaginella differentiated?
The plant body of Selaginella is differentiated into well developed roots, stem and leaves. Besides, some species also have rhizophore (Fig.7.46A).
What kind of rhizophore does a Selaginella have?
Besides, some species also have rhizophore (Fig.7.46A). Hieronymus (1902) divided the genus Selaginella into two sub-genera viz., Homoeophyllum and Heterophyllum on the basis of general structure of the plant body (Table 7.4). The stem is generally erect and radially constructed in the subgenus Homoeophyllum.