The largest stalks are about 10 to 35 microns long. For example the
stalk anchored at pixel
101,322 in
http://phoenix.lpl.arizona.edu/images/gallery/lg_23759.jpg
and anchored at pixel 119,326 in:
http://phoenix.lpl.arizona.edu/images/gallery/lg_23771.jpg
is about 9 pixels long.
The microscope image is 2 mm high by 1 mm wide, with 512x256 pixels.
See:
http://phoenix.lpl.arizona.edu/science_micro.php
One pixel is thus 1 mm / 256 = 3.91x10^-6 m = 3.91 microns. A 9 mm
stalk is 9 * 3.91 microns = 35 microns, or about 1.4 thousandths of
an inch. The diameter of a human hair ranges from 17 to 181
microns. The stalks are thus about as long as the width of a thin
human hair. They are about a pixel in diameter, or about 4 microns
wide, less than 1/4 the diameter of the thinnest human hair.
The matchstick lichen observed by Spirit had stalks about .5 mm in
length, or 500 microns. See page 4 of:
http://www.mtaonline.net/~hheffner/MarsLichen.pdf
So, the little "stalks" on the Phoenix stage are less than 1/10th the
size of the matchstick lichen stalks. This means they are likely
hyphal in nature, part of the hyphal mat that can anchor lichen to
almost any kind of surface. See: SueAnn Kingkade, "Exploring Lichens
With Scanning Electron Microscopy", Smith College, Fig. 6:
http://www.science.smith.edu/departments/SEM/pages/Sue/abstract1.html
It is further notable that some spore sizes are on the order of 10 to
100 microns (see Fig. 3 in Kingkade), bounding the size of the
approximately spherical bodies in the Phoenix photo lg_23759.jpg
referenced above, some of which appear to have matured, producing
hyphal material anchored right onto the stage. Pretty impressive, if
true, given the temperature.
Kingkade also shows some of the fibrous internal structure of a
thallus in Figs 9 and 10.
What a great 200 level course paper by SueAnn Kingkade.
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
