for any given observation the entire list of computer vision suggestions at a species level (not always returned if they are below some threshold) will add up to 100%. the higher-than-species suggestion is a sum of all the descendant species-level suggestions.
in this case, if you add the numbers for the species-level suggestions returned to you, you get 84.0%, which is just below the 84.2% genus-level number. (the excess 0.2% would be associated with other Trillium species not shown in this list.)