The scientific names of species are always italicized. The genus name is always CAPITALISED and is written first thus: GENUS species.
Your bookbinder will have trouble in providing gold lettering for the cover that is italicised or in lower case, so that is the only place you may break the rules.
If you write in caps then you need not to italize the botanical name...but if you write as in binomial nomenclature;the generic name beginning with first capital letter ,followed by specific name all in small letters..you may italize it or underline it.
There are official scientific rules how to write the binomial nomenclature:
In fact you should italicize scientific names of species. The genus name should always be capitalized and written first; the specific epithet follows the genus name and is not capitalized.
If you want more information on this topic I sould suggest to visit the following websites which could be of great use: