Populus is the heaviest figure in the geomantic set. All four of its rows hold a double point, giving eight points in total, twice the count of Via at the other extreme.
Reading the four rows
The rows are read from the top down as Fire, Air, Water and Earth. In the common reading a double point marks that element as passive in the figure, so Populus reads as all four elements passive together. Handbooks describe the result as a figure with no motion of its own, which is why it is so often glossed as the crowd, the gathering, or a situation that will do whatever is done to it.
What flipping it produces
Turn every row of Populus from double to single and you get Via. The two are the only figures in the sixteen whose rows are uniform, and they mark the ends of the range that the other fourteen fall between.
The attributions
This atlas records Populus under the Moon, the sign Cancer and the element Water, the same set Via carries. That the two opposite figures share a planet is one of the places where the astrological layer sits awkwardly on the point structure: the assignments were laid over the figures by later authors and were not derived from the rows. The handbooks differ on several figures, and this atlas records the common set rather than treating it as settled.
The Latin name means the people. Read in a chart, Populus is usually taken as a matter that depends on others rather than on the querent.