Pollen Morphology Training - Part 5: Additional Information

Summary

This video training session offers an in-depth look at pollen grain morphology, focusing on identifying key features such as reticulum patterns, aperture types, and sac morphology. It explores various aperture variations like sulcus and transverse compass, highlighting their differences. Additional topics include tetrad and polyad grains, their unique dispersal arrangements, and how the number of cells influences identification. Special attention is given to membrane ornamentation, reticulum size distribution, and the role of reticulum crisdaenam in grain morphology. The session aims to equip users with the knowledge needed to accurately identify and classify pollen grains based on these characteristics.

Takeaways

• 😀 Reticulum refers to a network of bridges creating depressions known as lumina, which can vary in size across the pollen grain.
• 😀 Homo-brocade grains have a uniform reticulum, while hetero-brocade grains show variations in reticulum size, either gradual or random.
• 😀 The reticulum size can differ across the grain surface, appearing smaller toward the pole and larger near the aperture, or vice versa.
• 😀 Reticulum can also have a special form called 'reticulum crisdam' with prominent sculptural elements present on the Murie.
• 😀 Secate morphology describes air sacs protruding from the body of a sac-like grain, which can vary from 1 to 3 sacs.
• 😀 Sulcus is an ecto aperture similar to a compass but with a different orientation, often found on monocot grains.
• 😀 An ulcerate aperture is a thinning of the exine that resembles a pore but is irregular in shape and may be described as a pore in the database.
• 😀 Compound apertures are formed by overlapping apertures in different layers of the grain wall and are documented in the notes section of the database.
• 😀 Aperture membrane ornamentation features a distinct pattern on the exine covering the aperture, which may differ from the surface pattern of the grain.
• 😀 Tetrad grains have unique dispersal arrangements, and their morphological description is based on a single cell while considering the tetrad formation.
• 😀 Polyad grains consist of multiple cells, and the number of cells can vary, aiding in pollen grain identification. Observing both polar and equatorial orientations helps ensure accurate cell counting.

Q & A

What is reticulum in pollen grain morphology?

Reticulum refers to a network of bridges (Murie) that create depressions known as lumina. It plays a key role in identifying pollen grains by their surface structure.

How can the homogeneity of reticulum affect pollen grain identification?

Grains with a homogeneous reticulum have a uniform reticulum size, making identification straightforward. In contrast, grains with a heterogeneous reticulum show variations in size, either gradual or random, which may complicate identification.

What is reticulum size distribution, and how does it vary?

Reticulum size distribution refers to how the size of the reticulum may change across the surface of the grain. The reticulum may be smaller near the pole and larger near the aperture or vice versa.

What is reticulum crisdaenam?

Reticulum crisdaenam is a type of reticulum that features prominent sculptural elements present on the Murie. This characteristic, if present, should be included in the notes section of the pollen grain database.

What is sac 8 morphology, and how does it differ from other structures?

Sac 8 morphology involves air sacs protruding from the body of the sac Hank grain. The number of sacs may vary, typically between 1 and 3. The main body of the sac is called the corpus, and it’s believed to function as the aperture.

What is a sulcus, and how is it described in pollen grain identification?

A sulcus is an ecto aperture that resembles a compass but differs in its orientation. It is commonly found on monocot grains and would be described as a compass in the database for identification purposes.

What is a transverse compass, and how is it classified?

A transverse compass is a ring-shaped aperture that is continuous around the equator of the grain. For identification purposes, it is described as sonner eight in the pollen grain database.

What distinguishes a compound aperture from other aperture types?

A compound aperture consists of multiple overlapping apertures occurring in different layers of the wall. This feature is described in the notes section of the pollen grain database.

How is aperture membrane ornamentation different from the grain surface?

Aperture membrane ornamentation refers to distinct sculpturing on the ex-im layer covering the aperture. This ornamentation often differs in pattern from the surface of the grain itself, providing additional identification clues.

What are tetrads, and how are they relevant in pollen morphology?

Tetrads are groups of four cells that occur in a specific dispersal arrangement. Morphological descriptions of tetrads are based on the aperture of a single cell, while the rest of the characteristics are based on the overall grain and its tetra formation.