Butia capitata
The most common Butia in cultivation, native to a large part of southern Brazil and Uruguay.
It grows in open areas or cerrado vegetation on sandy soils.
The non-cerrado populations in Southern Brazil growing on the coast in sandy soil clearly differ, and should be considered a separate species. See Butia odorata.
We can confirm that the Butia capitatas growing in the extreme south of Brazil are very different to the Butia odoratas along the coast.

The palm is considerably frost hardy, and grows to 6m tall , although in cultivation it can grow considerably higher.

Flowers yellow to mauve in colour , fruit ovoid, seed generally is round and containing up to 3 compartments.

The below pictures were taken in south Rio Grande do Sul, Brazil  where this form of Butia capitata is very common in cultivation, grown for its sweet fruits.

Although we found a couple of very old palms in gardens we couldnt find any growing in the wild ,although the locals said they had been brought from palms growing in the wild, and had been selected for the very large fruits. It seems likely there is wild populations along the extreme south of Brazil on the border with Uruguay.