Flowers and their nectar

[Ricko]

I've noticed while watching my bees work the Russian Olive bushes which are loaded with thousands of small flowers, when a bee works a specific flower and it is visited a few minutes later by another bee, it is quickly passed over. Does the first bee leave a marker for the next bee that the nectar pot is empty, or can a bee sense by smell that the pot is empty?
Secondly, does each flower replenish its nectar each day, or once the pot is emptied, does it stay empty for the duration of the bloom?

[artic]

I believe that bees leave a pheromone marker on a visited/nectar-less flower.

Though I'm not positive, I think flowers will replenish their nectar over time if they still have pollen or have not yet been completely pollinated.

[Curry]

The Almond Pollination Handbook says that bees will get most of their nectar from almonds days after the pollen has been stripped clean.

And, yes, nectar does replenish daily except in cases of lack of ground moisture, low humidity, or possibly cool temps. I understand that white dutch clover won't produce hardly any nectar unless it's 80 or hotter.

Given the right conditions, tulip poplar will create drops of nectar daily in the tulip cups... so much that you can sample it!