Flowers of Paris quadrifolia. The picture shows two flowers of the woodland plant herb paris. Each has four green petal-like perianth segments and four sepaloid segments (narrow, recurved) together with eight stamens, each with a yellow anther, the site of the pollen. In the centre of each flower is a purple-hued ovary surmounted by four stigmas. The flowers remain open for many days; if not pollinated by a passing insect, the stamens fold inwards to the centre of the flower so that the pollen they bear contacts the surface of the stigmas. This process of self-pollination is known as autogamy. It has potential genetic disadvantages, as there can be no increase in genetic diversity. However, the plant is well able to colonise a site by vegetative means due to its branching rhizomes. In a suitable shaded site in a garden, it may even become mildly invasive