Steve,

 I'd arrived at. Does the current really taper
away to zero at the open ends or is that effect swamped by ground

capacitance

when it's only 0.5% of a wavelength above ground?

The RF current at the open end of any wire is the vector sum of incident and
reflected energy.  Current "cancels" as that reflection co-efficient is
nominally "-1", whereas voltage doubles, as that reflection co-efficient is
nominally "+1".  That is the basic mechanism for a "standing wave".
Specific voltage and/or current distribution is influenced by the antenna
specific environment, but it would generally not be "swamped" by the likes
of ground capacitance, as wire segments "connecting to themselves" presents
a much lower impedance.

Mention of "displacement current" would probably be a red herring .....

73, Bob ZL2CA