Background Information

Pollen Structure: Pollen is produced inside of the anther of angiosperm flowers. Pollen grains come in all shapes and sizes. The pollen structure of different plants can help us figure out how closely related any given species are. Pollen grains can be anywhere from 6 micro-meters to 100 micro-meters. When pollen is released through the pollen wall, it goes through structures called apertures. By counting the numbers of apertures, we can also look at how closely related each species is. Pollen cells protected by a unique pollen wall. The pollen wall is made up of three parts: the outer exine wall, which is multilayered and broken up by apertures, an inner intine made mostly of cellulose, and a pollen coat made of lipids, proteins, and aromatic compounds. To capture pollen, stigmas engage biotic and abiotic pollinators and use adhesive interactions to retain pollen.

Our hypothesis is: the lily pollen will be similar in many aspects because the specimens are so closely related, but different in some aspects as well because they are different species.

Error Analysis.

Although our group worked really hard to limit the number of potential mistakes that our investigation had, it is inevitable that there were a few. When we used the SEM to measure our pictures we had to use our fingers to click what we wanted to measure. It is possible that during that time we clicked slightly different places to measure which would cause the information to be a little bit off.

Data Analysis

The goal of this experiment was to compare the structure of pollen in different species of Lilies.

We observed pollen grains from 3 different types of Lilies, Calla Lilies, Asian Lilies, and Day Lilies.
Each pollen grain is roughly the same size:
Calla Lilies: 110um
Asian Lilies: 109um
Day Lilies: (slightly larger) 124um

Both Asian Lilies and Day Lilies have an oval shaped pollen grain, while Calla Lilies have an almost trapezoidal pollen grain. HOWEVER, this could be due to damaged/crushed pollen.

Another noticeable difference is the presence of a fold down the middle of the Asian Lily pollen grain. This appears to be the aperture.
The Calla Lily also has this feature, but on the side of the grain.

The surface texture of each grain is also different.
The pollen from the Day Lily and the Asian Lily both  have a Reticulate surface texture while, the pollen from the Calla Lily is has a Verrucate surface texture.

Our original phylogenic tree that was based on pollen morphology matches the tree generated by rbcL comparison. This shows that the Calla Lily and the Asian Lily both share a later common ancestor. Our hypothesis was shown to be correct based on this data.
 

Protein Sequence Tree

Here is the tree we made using Jalview with the rubisco chain we found. It confirms the tree we made previously.

Hypothetical Evolutionary Tree of Lily Pollen

We believe that the Calla Lily and the Asian Lily are more closely related because they have similar pollen structure, the structure of the Day Lily is very different, suggesting that they have a more distant common ancestor.

Color-coded pictures:

Pictures by G.A.