This is a famous spike inflorescence in south India. It is quite common near the campus of Indian Institute of Science Education and Research present in Tirupati. The name of the plant is Amaranthus. These are a kind of inflorescence in which the flowers are sessile meaning does not contain any peduncle. It is also a racemose inflorescence. The stigma and stamen of this flower is also visible in this picture taken from the foldscope provided by the Central Govt of India. The magnification of this is not enough to see the pollen grains.
Pollen grains a very common weed in andhra pradesh. The name of the plant is Tridax procumbens commonly called as coat buttons.