Microscopy Forum

I.  I'm not sure about the genus, but my guess is that it might be Tribonema.  The right half of the image was cut then pasted below the left half to provide a larger view. 40x objective.

Bright field:

Cross-polarized light + retarder:

II. Flat colonial algae (a few micrometers thick) apparently covered by mucilage. Could this be a Pediastrum species?  40x objective.

Oblique lighting:

DIC:

Thank you, molehill, for your kind comments.  I have looked in four reference books that I have, and searched in Google Images for "green algae", "colonial algae" but, given that what I'm looking for is flat rather than globular, Pediastrum was the only thing that I found that came somewhat close, even though it doesn't look like the "proper" Pediastrum as shown in Seb Vasselle's recent image. Thanks again!

Hi Tony,

Thank you for your suggestions.  Unfortunately, both Eudorina and Stephanosphaera, as far as I could determine, are spherical or globular colonies. The images I posted are for a flat, one-cell deep (I believe) colony– perhaps 5 – 10 µm deep.  I thought that perhaps it was a species of Pediastrum because that was the only genus of colonial algae of this size that I could find that was flat (non-globular) and sheathed in mucilage, but that doesn't mean I'm right, of course (I rarely am).