Goldenrod (Solidago sp.) pollen. They are all perennials with large clusters of small yellow flowers that appear from the end of summer until frost. The leaves of goldenrods are simple, lance or egg shaped and usually have a toothed margin. Most species propagate by a spreading root system in addition to seed. They can be a troublesome addition to a wildflower garden for that reason. They become more common in pastures under heavy grazing pressure and so are used as an indicator species by range managers. Just about every insect with an interest in flowers may by found on goldenrod in autumn.