Operculum - seed appendages, Biology

Assignment Help:

Operculum - Seed Appendages

The term operculum is applied to a plug-like structure formed in the micropylar portion of the seed by proliferation of cells at the tip of the inner integument or the nucellus. An operculum has been observed in seeds of many monocotyledonous families, such as the Commelinaceae, Musaceae, Lemnaceae and Zingiberaceae, and a few dicotyledonous families like Bignoniaceae and Nymphaeaceae.

In Lemna paucicostata, cells at the tip of the inner integument undergo a remarkable expansion after fertilization and form a dome-shaped, stopper- like operculum. Cells of the operculum are thick-walled and contain an orange-red substance. During germination of the embryo the operculum becomes detached from rest of the seed and facilitates emergence of the embryo.


Related Discussions:- Operculum - seed appendages

Self-pollination - types of pollination, Self-Pollination - Types of Pollin...

Self-Pollination - Types of Pollination Self-pollination refers to the transfer of pollen grains from the anther to the stigma of the same flower. In chasmogamous flowers the

Glycogen synthesis, To synthesize glycogen two enzymes are needed: 1.  U...

To synthesize glycogen two enzymes are needed: 1.  UDP-glucose   pyrophosphorylase catalyzes the synthesis of UDP-glucose from UTP and glucose 1-phosphate:   The   py

Define functions of vitamin d, Define Functions of Vitamin D? Vitamin D...

Define Functions of Vitamin D? Vitamin D is required to maintain normal blood levels of calcium and phosphate, which are in turn needed for the normal mineralization of bone, m

Epiboly - mechanism of gastrulation, EPIBOLY - The epibolic movement...

EPIBOLY - The epibolic movements occur only in the prospective ectodermal blastomeres. In the blastula of frog, migration and rearrangement of microceres over megameres i

Explain with reference to aquatic ecosystem, That is eutrophication? Explai...

That is eutrophication? Explain with reference to aquatic ecosystem. or Name any two source organisms of agar. List any four areas in which agar has wide application.

Draw a diagram of transverse section of mammalian bone, Draw a diagram of t...

Draw a diagram of transverse section of mammalian bone and label the following parts in it: (i) Haversian canal (ii) Lacuna containing osteocytes (iii) Canaliculi

Crucial periods of a woman''s life - pregnancy and lactation, Define crucia...

Define crucial periods of a woman's life - pregnancy and lactation? In this unit, we studied about the most crucial periods of a woman's life, pregnancy and lactation, especial

Administer accurate and appropriate antibiotics, Administer Accurate and Ap...

Administer Accurate and Appropriate Antibiotics: Appropriate antibiotics to which organism isolated from sputum or bonchoscopic aspirate, is sensitive are administered for 4-6

What is immune memory, How can an organism that once underwent contact with...

How can an organism that once underwent contact with an antigen be immunized against future infections by the same agent? This phenomenon is known as immune memory . When an a

Porcine rotavirus, Porcine rotavirus Piglet diarrhoea and mortality are ga...

Porcine rotavirus Piglet diarrhoea and mortality are gaining importance and the viral agent which is highly incriminated in such episodes is porcine rotavirus. The clinical featur

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd