In message , Nick Maclaren
writes

There are a lot of variations in the names, but the first two are
always genus and species, and then subspecies, variety, tribe and other
arcane distinctions.

Tribe and subtribe are the next formal ranks up from genus.

To clarify further (for the original poster) a botanical name is

Genus species [subsp. subspecies] [var.variety] [f. form
[subf. subform] [(original author - at a different rank, or in a
different genus)] author

(I haven't seen any occurrences of subvarieties.)

Some plants don't form nice, neat groups and their classification is
almost entirely a matter of taste (brambles are an extreme example).

Other problematical groups are eyebrights, hawkweeds and dandelions.
(For that matter no-one seems to have a good handle on how to classify
hollyhocks and Sidalceas.)

--
Stewart Robert Hinsley