Green pockets with seeds

Abstract

While conducting field research on plants in China's western Sichuan Plateau during July 2022, we observed the perennial herb Przewalskia tangutica (Solanaceae) with pocket-like green bracts (hereafter, “green pockets” or simply “pockets”). Each plant had multiple green pockets, and each green pocket contained a single fruit along its interior base. Interestingly, we found that the pocket would naturally fall off the plant once its fruit was mature. Then, as the pocket—now disconnected from its plant—gradually desiccated, it became so light that it could easily be blown far away by the wind. A few days after gaining its independence, the pocket almost entirely decayed, leaving only a mesh-like framework of veins, thereby allowing the seeds to escape. This finding suggests that the pocket plays a role in seed dispersal and promotes the spread of P tangutica, an imperiled species found at high elevations and subject to overharvesting due to its medicinal properties. However, some questions remain unanswered. Because each pocket has a small mouth-like opening at its top, if rain falls into a pocket, does it affect fruit and seed development? Does the green pocket contribute resources (such as carbon and energy) to fruit and seed development through photosynthesis? Was the evolution of the pocket driven by harsh physical conditions (such as low temperatures, ultraviolet radiation from intense sunlight, or heavy rains) on the plateau? Does the pocket provide protection against potential seed predators?