Umbelliferous
Cow-parsnip (Heracleum maximum) belongs to the plant family Umbelliferae, the parsley family. In this plant, umbellets combine to form a compound umbel. I checked the spelling of 'umbelliferous'. Two ll's is correct.
I hope the full size source images give a better idea of what I mean by compound umbels. Basically a big 'spray' made up of little 'sprays'.