Also, if the insured is afforded coverage under the additional coverage, and the number of mature plants the insured had exceeded the limit allowed by law, would we still owe for the mature plants he had or just owe the limit?

California Subscriber

The policy does not define trees, plants, or shrubs, and Merriam Webster Online defines "plant" as "a tree, plant, shrub, or herb planted or suitable for planting." Since marijuana is dried and used like an herb, we say it falls under the coverage for trees, plants, and shrubs.

The policy does not get into legal issues, so whether the insured was over the legal limit of plants does not factor into coverage; there is no exclusion for plants over the legal limit. The insured should be compensated for the plants he had, and it is up to law enforcement to deal with the over the limit issue. However in California a doctor can authorize a patient for more plants than the legal limit, so that may have been what happened here. You may find this article interesting.