G'day Stephen,

You wrote: ... Surely it's best to pull the entire
plant out, roots and all?...

The clovers are legumes adding both nitrogen and organic matter to the soil,
why not leave it there?

You wrote:...but bindii seeds exist on the plant, not
underground in the roots.

Yes, but the insects and the elements store much seed below the ground, the
first for storage and the later for opportunity.

The less you disturb the soil surface, the less weed seeds you will
unearth.

China
Wingham
NSW