Pollination is generally defined as the transferring of plant pollen grains from the male part (anther) to the female part of a flower (stigma), with an intention of reproducing more plants (Waser et al. 1996). According to Stanley et al (2016), pollination is a mutual benefit for plants and pollinators, where plants gain the service and pollinators get food as a reward from plants. Many legumes have been found to have evolved flowers with explosive pollination mechanism (Stanley et al. 2016). Different pollinators have also been reported to activate or trigger the explosive mechanism, such as, bees, birds, flies, butterflies, moths and sometimes wind (Willmer et al. 2009). Many species in the tribe Desmodieae have been found to have explosive mechanism for pollination, including G. setigera (Schrire, 1984).

Grona setigera is observed to exhibit a change in flower colour after being pollinated. The flowers are mostly visited by different bee species for pollination to take place. An explosive mechanism happens on G. setigera flowers during the pollinator’s visitation (Stanley et al. 2016; Willmer et al. 2009). When the pollinator lands on the keel part of the flower and probes for nectar, it disturbs or trips the flower, which exposes the reproductive parts of the flower, the anthers and stigma, and pollen is released on the visitor (Willmer et al. 2009). When a flower has been visited by the pollinator, its colour changes rapidly from lilac to white, but if it is unvisited, the flower changes colour slowly, with lilac persisting throughout the day becoming dark turquoise (Willmer et al. 2009). The colour change of the flowers is believed to be a signal to pollinators that the flower has been visited and nectar is no longer available, as a result, nectar is not wasted as it is very costly for the plants to produce (Stanley 2016). Flowers of G. setigera that are visited early in the morning but not adequately pollinated allows a second chance of pollination later in the day, where the plant is able to reverse the colour change, signalling to insects that nectar is available, so that the flower can be revisited when pollination was not successful on the first visit (Willmer et al. 2009).