Arabidopsis thaliana bolting for flowering - about two weeks old and 2-3 cm tall (plants were grown on Metromix soil under long-day conditions in a growth chamber)
I just love the way Arabidopsis is covered with all those little trichomes. They're long and straight on the stem and Y-shaped (actually more trident-shaped with three points) on the leaves. Look at the full size image for a better view of those teeny tiny details or check out some of the other images in my Arabidopsis set.
This picture was taken inside a growth chamber.