Higher light equalling bushier growth makes logical sense, because that's what we expect with terrestrial plants - shaded plants grow more taller and thinner, trying to reach for the light.
But the exact reverse appears to be true with my aquatic plants though. Or at any rate, it's not the light at all, but the CO2 levels.
Here I can make a direct comparison between cuttings from the exact same original Sessiliflora plant. Some in a high light / high CO2 tank, the other in a non CO2 tank. Compare:
Whether the light in the high CO2 tank (left) was 7w/g or reduced to 3.5w/g made no real difference to the stem distance between leaf nodes, which is on average about 5 to 6cm. The stronger light simply made the growth faster, with no difference to the actual growth pattern - long non-branching stems.
In the other tank (right), you can see a totally different growth pattern to a cutting taken form the identical plant. With what can be considered high light at 3w/g, the growth is far bushier, the spread of the leaves is greater and the stem distance between leaf nodes is less than 1cm. And there's a small branch developing. Overall speed of growth is far slower too.
Apart from just 0.5w/g difference in light and the (non)presence of CO2, all other factors except NO3 can be considered equal (the NO3 is actually lower in the more stemmy growth tank, Scolley).
My conclusion is it must be the CO2 which promotes growth speed which translates as stem growth. So high light does indeed promote bushier plants, but not with high Co2.
Robert H, I also have two Marble Queen swords as examples too, taken from runners from the same parent plant. One is in the same high CO2 27ppm, 3.5w/g light tank has a stem of approx 16cm before the leaf actually begins. The other plant of equal size in another tank also with CO2, but only half as much at 12ppm, and 3w/g light has a maximum stem length of 8cm on all its same sized leaves. Literally, half the CO2 is producing half as long stems.
These are just my own personal observations.