For example, I have Blyxa japonica growing in a lower flow region, and one where there is stronger downwelling current.
There is a huge difference in morphology, rates of growth and appearances.
The higher flow rates suppress growth even though the light is more intense, good CO2/same sediment and water column nutrients. Color is different also.
While light is some of it, I placed the same plant in the same tank over where there is less flow, it reverted back to the form in the other tank.
I like the slower and lower growing less weedy growth.
For some species, the effect of current is very pronounced.
While I have 3500GPH of flow in the 180 Gal tank, it's low pressure even high flow, much like the flows one might find in a moderately flowing 0.5-1 knot stream.
The plants grow really large in that tank.
In the other tank there's a high pressure of flow in one corner and the plants do very well there, but tend to stay small/short. I think higher flows cause the plants to grow more roots and more prostrate along the sediment instead of up/more leaves. They'd just lose the leaves and have them stripped off if they did not modify their growth forms for current.
Most all swords/Crypts and Anubias are river/stream plants, so this is why they have strong roots and storage, not solely because they prefer root uptake. They have little choice as to sediment uptake when the dry season starts also.
Regards,
Tom Barr