Washingtonia Robusta trunk bass

[Coasta]

What determines how thick the bottom of a Washington robusta is. I see some bases that are pretty wide then they get skinny with height, and others that are really thin at the base. 

[aztropic]

Genetics and available water.

 

aztropic

Mesa, Arizona 

[Coasta]

If I don't provide supplemental water, will it stunt it?

[Jim in Los Altos]

Many of the fatter Washingtonian robusta are actually hybrid robusta x filifera or vice versa. So genetics plays a major role in their trunk widths.