Image 1. A photo of the lilium candidum from which the pollen sample was extracted.
The pollen sample was taken from a lily (type species: lilium candidum) (Image 1) found outside the Broad Center for the Biological Sciences at the California Institute of Technology (Caltech) in Pasadena, California at 8:10 p.m. on Thursday, May 9, 2019. The sample was obtained by removing the stigma and style of the flower and scraping the pollen from the stigma onto the microscope slide with a needle. The species of the pollen is likely a Division VI cross hybrid known as trumpet lilies, similar to lilium regale, as found through an image search and via Wikipedia ( https://en.wikipedia.org/wiki/Lilium) .
Image 2. A photo taken with an iPhone camera through the lens of the foldscope of the lily pollen with a small amount of light behind the sample.
The magnification of my foldscope is 140× . The dimensions of the photo is 3024 × 4032 pixels. With a 300 dpi camera, these dimensions translate to a 0.256× 0.341 m photo (I used an online calculator to find the unit conversion). I used the ‘select’ feature of the Preview application on MacOS to roughly outline a grain of pollen, to find that its dimensions are roughly 237 ×81 pixels, which translates into .020×.007 m photo. With a 140× magnification, this means that the pollen grains are actually 0.00014× .00005 m in size, or 142× 50 microns.
Image 3. A photo taken with an iPhone camera through the lens of the foldscope of the lily pollen with a small amount of light behind the sample.
My images aren’t good quality due to difficulties encountered with the use and quality of the foldscope. Because of this, it would be preferable to use a better microscope with a higher resolution to learn more from my image.
However, I am still left with a few questions about the lily pollen. Specifically, I would like to learn more about how the shape of the pollen affects its function. It’s a rice-like shape and I am curious as to how that contributes to the function of pollen as male microgametophytes (essentially, plant sperm). Would this shape differ with different plants? If so, would the different shape impact whether certain crosses of plants occur? Would this shape positively impact breeding between plants of the same species? To answer this question, I would likely take more samples of pollen from different plant types to see whether there is any dramatic difference in size or shape. From this, I could explore more methods to answer my latter questions, such as possibly taking cross sections from the style of different flowers.
From my images, I also only see the outside of the pollen. Does the inside of the pollen grains differ from the outside? If so, how does this impact the function of the pollen? I could answer these questions by exploring methods of cutting the small pollen grains and using a microscope to look at the cross section of the pollen grains. As for the function of the pollen, I would use a method to find the protein structure of the pollen’s different parts and study, for example, the polarity of these structures and hypothesize how they interact.
Image 4. A photo taken with an iPhone camera through the lens of the foldscope of the lily pollen with a medium amount of light behind the sample.
This activity inspires many questions about the function of flowers. As such, it’d be very interesting to take samples of various parts of a flower to see more information about the microscopic features of plants. I would also like to do so with more sophisticated equipment and explore the protein structure of various parts of the plant to get a more informed overview of the role pollen plays in the overall function of the plant.
#caltechbi1