[Home]
[Up]

Fig. 6.3-2. Longitudinal section of a shoot tip of horsetail (Equisetum arvense, also called scouring rush). Like ferns, equistems are plants that reproduce with just spores, not seeds, and similarly, their shoot apical meristems have a prominent apical cell. The cell itself is not particularly easy to see in this micrograph, but notice cells (and their nuclei) on either side: all the cells are rather flat and brick-shaped, and they are oriented parallel to the sides of the apical cell. In the apex of Nephrolepis (Fig. 6.3-1b), the lateral progeny cells quickly undergo a transverse division, but here they do not do that, so it is easier to see that these cells are related to the apical cell.

            On the right side, the two very dark red masses are the two nuclei re-forming in the latter stage of nuclear division (arrow; this is anaphase -- the dark mass between the two nuclei is the spindle). Notice that this division will produce an outer cell and an inner one -- the outer cell will start the formation of a leaf at this site. All the nuclei here have small dark red splotches -- those are nucleoli. Look carefully at a set of nucleoli -- you will see a slightly darker mass of gray material, which is the nucleus itself. The nuclei have been stained almost the same color as the cytoplasm, which is unusual; typically nuclei stain red and cytoplasm stains blue/green.