Field pennycress flowers. Coloured SEM (scanning electron micrograph) of field pennycress (Thlaspi arvense). The flowers house the male reproductive organs (stamens), which are each topped by a pollen sac (anther, brown). The flowers also contain the female reproductive organ (carpel), which receives pollen on its tip (stigma, yellow, lower right). Pennycress is considered an agricultural weed that grows on waste ground and headlands throughout Europe, USA, eastern Asia & northern Africa. It is also known as the stinkweed due to its unpleasant smell. It may be used as a salad leaf, but can be poisonous to livestock. Magnification: x9 at 6x7cm size.