Today, we’ll be taking a closer look at a fasciated Haworthia succulent, also known as the “zebra succulent”. This imaging adventure was undertaken as a part of our Diagnostic Devices and Imaging lab course.
This is the plant we will be imaging:
The Haworthia succulent is akin to aloe vera. It has a similar spine-like structure, which is filled with a jelly-like substance. To image this plant, the following materials were used:
The leaf, shown in the image above, was prepared on a glass slide. The glass slide was then loaded into the foldscope for imaging. Adhesive stickers, provided with the foldscope kit, were used to mount the sample onto the glass slide. Scissors were used to cut a cross-section of the leaf.
To begin, the glass slide was lightly pressed against the foldscope lens to decrease distance between the specimen and the lens. This strategy facilitated focusing on the image. A magnetic cellphone camera mount was used to easily couple a phone camera and the foldscope lens. Images were obtained using a Samsung Galaxy S21 Ultra phone.
With strategic positioning, we can begin to see the interface between the chloroplast-abundant leaf layer and the gelatinous substance that fills the leaf (similar to aloe jelly). The image below clearly shows the interface of the leaf encasing and the interior jelly substance.
In an attempt to view cells in the plant, a pseudo- phase contrast approach was adopted. Rather than shining the light directly on the specimen, the specimen was slightly tilted away from the light to cast slight shadows and increase contrast of small structures in the sample. Using this strategy, plant cells became visible as seen below.
In these images, one can appreciate that although the cell layer and gelatinous substance layer are separated, bubbles can be seen throughout the cross-section. This is likely to facilitate water and nutrient transport in the succulent since such plants are expected to survive extended periods of time without water.
Finally, it was possible to obtain a closer look at the filamentous extension alluded to earlier. Below is a magnified image of the filament:
Overall, this imaging adventure provided further insight into the Haworthia succulent’s microscopic structure. It was observed that the leaf consisted of an outer plant cell layer, filled with a gelatinous substance. The plant cell layer consisted of highly organized, hexagonal cells, with varying shades of green – indicating varying levels of chlorophyll production. Although the gelatinous layer was largely separated from the plant layer, some gel bubbles/pockets, were visible in the plant cell layer. Finally, fibrous filaments run through the plant cell layer to provide structural support and rigidity.