What euphorbia species can hybridise?

For example:

Can euphorbia obesa cross pollinate with euphorbia pachypodioides?

Can euphorbia ammak hybridise between euphorbia cylindifolia?

Can euphorbia bupfleurfolia hybridise with euphorbia ferox?

What about euphorbia polygona with hedyotoides?

Or euphorbia stellata with stellaspina?

Perhaps euphorbia milii and euphorbia ankarensis?

I can only image what these could look like!