ligules

[Robert Haynes]

I was asked to share the info from Gifford and Foster.  As I said
earlier, there are several paragraphs developed to this but I will
summarize or at least pick certain parts


"At maturity, a ligule is a surprisingly complex structure,
considering its small size and short life.  The ligule may be to some
extent sunken in the leaf and has a basal sheath of cells with
casparian strips and an adjacent group of large, vacuolated cells
termed a glossopodium ....  The sheath cells resemble endodermal
cells and may well perform a regulatory role in the movement of water
and dissolved substances.  The frequent development of trachiedlike
cells (transfusion tissue) between the ligular sheath and adjacent
vein of the microphyll strenghtens the concepts of direct conduction
of substances to the base of the ligule.

A ligule develops precociously soon after initiation of the
microphyll, and it has been assumed that it might function as an
excretory structure in keeping the young leaf primordium (and
sporangium of a sporophyll) moist during early development.  There is
now convincing evidence that the ligule in certain species, during
early development, secretes a mucilage consisting of carbohydrates
and proteins which also coats the apical meristems ...."
Robert R. Haynes
Director of the Herbarium
Box 870345
The University of Alabama
Tuscaloosa, AL 35487-0345

Voice:  (205) 348-1826
Fax:    (205) 348-6460

rhaynes at biology.as.ua.edu