Flavors from low pitching rate?

I did a search and didn't find anything specifically about this. What flavors can you get from a low pitching rate, if any? Designing Great Beers it discusses recommended pitching rates but does not address what specific problems you can have from not pitching the required amount.

I did a fairly large beer yesterday (1.067) and didn't do a starter with the dry yeast I used. Everything was bubbling away this morning but I wasn't sure if I might not get some off flavors from it.

I think the bigger issue with underpitching is not having a healthy enough colony of yeast to get the job done, that they'll be too stressed by the job in front of them that they'll poop out early.

Not really sure what off-flavors are possible exactly. If you are using dry yeast, why not just use two packages for a big beer? They are cheap.

Underpitching can cause stressed yeast. Stressed yeast can cause many off-flavors, as well as cause underattenuation. Some of the off-flavors would be by-products of fermentation, like diacetyl, fusel alcohols, esters, phenols, soapy flavor (from the breakdown of lipids), etc. Those are all common flavors as byproducts of fermentation, but healthy yeast produce less of them and then still work to "clean up" those after fermentation is finished. Stressed yeast just can't do the job properly.