| Heterosporous lycopods have small flaplike organs borne
on their upper leaf surfaces called ligules.
These structures develp before the leaves become mature
and are thought by some to be invovled in secreting mucilage and keeping
the young developing leaf moist.
In this photo you can see
a ligule in longitudinal section.
In Isoetes, ligules often have an inflated base,
seen here, called a glossopodium that is absent in Pennsylvanian lycopods.
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for next photo. |
