1. Consider Relationship and Context: Evaluate your relationship with this opposite sex friend and the context in which he/she sent flowers. If the relationship between the two parties is pure and the gift of flowers is for a legitimate reason of friendship or celebration, it may be considered to accept it.
2. Personal feelings and comfort: Consider your own feelings and comfort level towards this action. If you are happy with this gift and willing to accept it, then accepting it is appropriate. If you feel uncomfortable or have concerns, you should communicate openly and express your feelings.
3. Avoiding misunderstandings: Clarify the meaning of sending flowers and ensure that both parties have the same understanding of it. If unsure if there are other meanings (such as romantic pursuit), politely ask or choose to decline to avoid unnecessary misunderstandings and embarrassment.