What stele is found in pteridophytes?
Protostele: The type includes Haplostele, Actinostele, Plectostele, and Mixed protostele. (i) Haplostele: Xylem surrounded by phloem is known as haplostele. Example: Selaginella. (ii) Actinostele: Star shaped xylem core is surrounded by phloem is known as actinostele.
How many types of stele are there in pteridophytes?
Tieghem and Duoliot recognized only three types of steles. They also thought that the monostelic shoot were rare in comparison of polystelic shoots. But now it is an established fact that most shoots are monostelic and polystelic condition rarely occurs.
What is stele describe the evolution of stele in pteridophytes?
The term stele refers to the central core of plant axis and is restricted only to primary tissues. The term is used in case of pteridophytes and is seldom applied in case of angiosperms and gymnosperms. Endodermis delimits a stele on the peripheral side.
What is stele and write its types?
Solution : The term Stele refers to the central cylinder of vascular tissues consisting of Xylem , Phloem, Pericylcle and sometimes medullary rays with pith . Two types : 1. protostele: (i) Haplostele : Xylem surrounded by phloem is known as haplostele. Eg: Selaginella.
What is in the stele?
In a vascular plant, the stele is the central part of the root or stem containing the tissues derived from the procambium. These include vascular tissue, in some cases ground tissue (pith) and a pericycle, which, if present, defines the outermost boundary of the stele.
How many major types of stele are?
There are three basic types of protostele: haplostele (FIG. 7.32), actinostele, and plectostele (FIG. 7.33). In a haplostele, the xylem is circular in cross section or cylindrical in three dimensions; phloem is immediately outside the xylem.
What is stellar theory in pteridophytes?
Definition of Stelar System: According to the older botanists, the vascular bundle is the fundamental unit in the vascular system of pteridophytes and higher plants. Van Tieghem and Douliot (1886) interpreted the plant body of vascular plant in the different way.
What is the importance of stele?
stela, also spelled stele (Greek: “shaft” or “pillar”), plural stelae, standing stone slab used in the ancient world primarily as a grave marker but also for dedication, commemoration, and demarcation.
What is the function of the stele?
The stele functions in the transport of water, nutrients, and photosynthates, while the cortical parenchyma fulfills metabolic functions that are not very well characterized.
What is Hammurabi’s stele?
A stele is a large carved piece of wood or stone that contains information about a particular society. The oldest written law code in the world, Hammurabi’s code, was carved on several steles and displayed in public locations. Hammurabi’s code influenced every aspect of life in Ancient Babylon.
What does the stele of Hammurabi say?
The Hammurabi code of laws, a collection of 282 rules, established standards for commercial interactions and set fines and punishments to meet the requirements of justice. Hammurabi’s Code was carved onto a massive, finger-shaped black stone stele (pillar) that was looted by invaders and finally rediscovered in 1901.
What is stele in botany?
The plant stele consists of the primary vascular system of the plant axis (stem) and its associated ground tissues (e.g., pith). The stele consists solely of primary tissues differentiated from procambial strands derived from the apical meristem.
What are the different types of stele found in pteridophytes?
There are several types of stele found in pteridophytes which are: 1 Protostele 2 Siphonostele 3 Solenostele 4 Dictyostele 5 Polycyclic stele 6 Eustele 7 Polystele
What is Stelar organization in pteridophytes?
This type of stelar organization is the most complex one amongst all vascular cryptogams (pteridophytes). Such type of steles are always siphonostelic in structure. A typical polycyclic stele possesses two or more concentric rings of vascular tissue. This may be a solenostele or a dictyostele.
What are the protostelic conditions of pteridophytes?
Majority of the pteridophytes show protostelic conditions in their rhizome, stem or roots. This is the most primitive type of protostele. Here the central solid smooth core of xylem remains surrounded by uniform layers of phloem (e.g., in Selaginella spp., Gleichenia, Lycopodium).
Which of the following is the primitive type of stele?
According to him, the primitive type of stele is protostele. In protostele, the vascular tissue is a solid mass and the central core of the xylem is completely surrounded by the strand of phloem. This is the most primitive and simplest type of stele. Pith is absent in protostele i.e. it is non-medullated.