What is peristome and its function?
The peristome is a specialized structure in the sporangium that allows for gradual spore discharge, instead of releasing them all at once. Most mosses produce a capsule with a lid (the operculum) which falls off when the spores inside are mature and thus ready to be dispersed.
What is Epicranoid peristome?
What is epicranoid peristome? Ans. In this type, there are two rings of peristome teeth—an inner endostome and outer exostome. The endostome is a more delicate membrane, and its teeth are overlapped by the teeth of the exostome.
What is peristome teeth Funaria?
32 teeth in 2 rings.
What is peristome teeth where it is found?
The peristome is a teeth–like projection that surrounds the mouth of the capsule in most of the members of Bryidae (Mosses) of bryophytes. So, it is an important characteristic of Bryopsida. The peristome teeth spring from the rim or diaphragm.
What is the function of Elaters?
Elaters are the ribbon or tube like structures attached to the wall of spore. The elaters function is to increase dispersal because they push the spores out of the plant by absorbing moisture.
How many Teeths are found in peristome?
In the order Polytrichales the peristome consists of 32 or 64 short, pyramidal, solid teeth. Each tooth has a central pillar of fiber-like cells.
What is Nematodontous peristome teeth?
When the teeth of peristome are solid structures. composed of bundles of dead cells, it is termed nematodontous peristome are solid structures composed of bundles of dead cells, it is termed nematodontous peristome. It is found in polytrichum, Pogonatum and Tetraphis.
How many teeth are found in peristome?
What is difference between elaters and Pseudoelaters?
Elaters and pseudoelaters are sterile cells, where they combine with spores and release into valves, Elaters are usually present in hepaticopsida whereas pseudoelaters are present in Anthocerotopsida.
What are true elaters?
An elater is a cell (or structure attached to a cell) that is hygroscopic, and therefore will change shape in response to changes in moisture in the environment. Elaters come in a variety of forms, but are always associated with plant spores.
What is Nematodontous peristome?
Each peristome is a ring of triangular “teeth” formed from the remnants of dead cells with thickened cell walls. In other groups of mosses, the capsule is either nematodontous with an attached operculum (as in the Polytrichopsida), or else splits open without operculum or teeth.
What are the two types of arthrodontous peristome?
There are two subtypes of arthrodontous peristome. The first is termed haplolepidous and consists of a single circle of 16 peristome teeth. The second type is the diplolepidous peristome found in subclass Bryidae.
Where is the mouth located in a starfish?
Above: the oral surface of a starfish. The mouth is visible in the centre of the disc, in the middle of a circular or pentagonal peristomial membrane or peristome (shown in darker orange). A groove, called the ambulacrum, extends from the tip of each arm toward the peristome.
How are the podia of a starfish arranged?
In some species the podia are arranged in tightly zig-zagged rows, giving the appearance that there are four rows of tube-feet in each ambulacrum. These podia act like many tiny feet and their walking movements propels the starfish along. The ambulacra are lined by rows of spines, which may move to close over the ambulacral grooves.
Are there any mosses with no peristome teeth?
In this type, there are two rings of peristome teeth—an inner endostome (short for endoperistome) and an exostome. The endostome is a more delicate membrane, and its teeth are aligned between the teeth of the exostome. There are a few mosses in the Bryopsida that have no peristome in their capsules.