Please check the following link and PDF attachments.

https://www.researchgate.net/post/Conservation_status_of_species-is_the_IUCN_Red_List_complete

thank you Sir..

 https://www.cbd.int/doc/publications/plant-conservation-report-en.pdf

https://portals.iucn.org/library/sites/library/files/documents/RL-2004-001.pdf

To determine conservation status of a species, the best viable approach is following IUCN Red List Assessment Methodology. Please check with IUCN Website for detailed methodology.

For the experience I had in Italy, the only way to put under protection in a serious way the flora (especially the herbaceous species), two actions: A - identify the areas with the highest concentration of rare and endangered flora (habitat census ); B - prohibit the collection of any flora within these areas.

The method to prohibit the harvesting of certain species through lists of scientific names is useless, because most people do not know the scientific names of certain species.

Best, Gianluigi

thank you for the suggestion, Mr.Gianluingi 

Thank you so much for sharing the references, Mr.Selim.

Dear Monalisha,

the best way to assess the conservation status of certain species is to follow the rules of  the guidelines for Using the IUCN Red List Categories and Criteria. Version 1. avaliable online in:

http://www.iucnredlist.org/documents/RedListGuidelines.pdf

Dear Lulezim, I accept your point. Thank you, Mona