Some species can be challenging to collect at the right time. Seeds might be unripe until the time when suddenly fruits open up and send their seeds far away. It can be difficult to get to the field during that short period of time when seeds are ripe enough but still on the mother plant.
In these cases it is possible to go to the field prior to the ripening stage and place gauzes or mesh bags around immature fruits, closing them at the base with a string, being careful not to harm the plant. When fruits open, seeds will fall into the gauzes or mesh bags, where you’ll be able to collect them easily. Make sure to mark the plants so that you can find them on your return. Avoid leaving the seeds in the gauzes for too long after dispersal, as they will age. Go periodically to the site to check the ripening stage, and be aware that usually these kinds of fruits open on a very dry, sunny day!