Count unique point field values in polygons

In some vegetation point layer I have attribute field with plant species. Every point one plant of some specie.
I have some areas polygon layer too.
In one polygon i can have for example specie A two times, specie B seven times, specie C five times.
In another there is no specie A, in another there is no specie D .....

I want to ArcGIS count how many species are in each polygon, not how many plants are there.
Another words, to count how many unique points are in polygon.

Is this possible?
Thanks in advance :)