door guardian1967 op 04 nov 2019 08:49
the color of the leaf alone is usually enough. Jubaeas have very deep green leaves that I have never seen on any Butias (relatively pale, blue-grey etc.). Also Jubaea leaves tend to be straighter (arching more with age) and very stiff (Butia leaves are softer and arch, even at a younger age). Jubaeas tend to hold a lot more leaves than a similarly sized Butia (nearly twice as many) making their crowns a lot denser). Butia seedlings tend to have very thin leaflets while those of a Jubaea are nearly twice as wide (this difference fades a bit with age). Also Jubaea leaflets are reduplicate. This means they are folded into a V shape on cross section the entire length of the leaf and the V is pointing down towards the ground (as opposed to the sky or the direction Phoenix leaves point- Induplicate). Butia leaflets are not even folded, or just barely so just at the base where they come off the petioles. I have never had a problem telling these two apart, but Jubaeas can look a LOT like Phoenix canariensis at smaller sizes (leaflet reduplication is a good giveaway there, as are the spiny leaf bases on the Phoenix).
Butia x Jubaeas are much trickier to tell apart as these have variably arched leaves- or sometimes not, can have pale leaflets... or sometimes not, and the leaflets are less obviously folded into a V shape...