the.com/tributaries
The streams that pay their watery taxes to a greater river.
means Smaller rivers or streams that flow into and feed a larger body of water.
from From Latin tributarius, one who pays tribute — these waters literally hand over their flow to a bigger ruler, the main river.
Amazon's armyOver 1,100 tributaries swell the Amazon.
Word cousinShares roots with tribute and tax.
Opposite actDistributaries split off instead of joining in.