There are several online platforms and forums where you can discuss Botany-related questions for the UPSC optional subject exam. These platforms provide a space for aspirants to interact, share knowledge, and seek guidance from experts in the field. Here are some popular platforms you can explore:

1. EduRev Botany Community:
- EduRev offers a dedicated Botany community where you can connect with fellow UPSC aspirants and discuss all aspects of the subject.
- You can post your queries, participate in discussions, and get answers from experts.
- The platform also provides study materials, practice questions, and previous year question papers to help you in your preparation.

2. Quora:
- Quora is a popular question-and-answer platform where you can find a community of people interested in Botany and UPSC exams.
- You can post your questions related to Botany and UPSC optional subject exam and get answers from experts and experienced individuals.
- Remember to search for relevant topics and questions before posting, as there may already be discussions on the subject.

3. UPSC Forum on ClearIAS:
- ClearIAS, a renowned UPSC preparation platform, has a dedicated forum where you can discuss various subjects, including Botany.
- You can ask your doubts, share study resources, and interact with fellow aspirants preparing for the UPSC exam.
- The platform also provides guidance and tips for effective preparation.

4. UPSC Discussion Group on Facebook:
- Facebook groups focused on UPSC preparation are a great way to connect with a large community of aspirants.
- Look for groups specifically dedicated to Botany or UPSC optional subjects.
- These groups allow you to post questions, share study materials, and engage in discussions related to the subject.

Remember to follow the guidelines and rules of each platform to maintain a healthy and productive discussion environment. It's important to be respectful and considerate towards others while seeking and providing information.

In conclusion, platforms like EduRev Botany Community, Quora, ClearIAS forum, and UPSC Discussion Groups on Facebook are excellent online platforms and forums where you can discuss Botany-related questions for the UPSC optional subject exam. These platforms provide opportunities to interact with like-minded individuals, seek guidance, and enhance your understanding of the subject.