Vanilla (Vanilla planifolia) is the second most valuable spice in the world. While artificial vanilla is widely used in manufactured food this contains just the chemical vanillin, whereas vanilla pods containing other aromatic chemicals have a more rounded flavour. Vanilla pods, sometimes called vanilla beans, are the fruit of a climbing orchid native to Mexico. Orchid seeds are tiny and rely on mycorrhizal fungi for nutrients, so vanilla is propagated by cuttings. In Mexico vanilla is pollinated by hummingbirds and certain bee species, but outside their native range pollination and yield is low. Added to this, vanilla flowers are fertile for just one day. Unsurprisingly early attempts to introduce the crop to other parts of the world failed. It was only when hand pollination was introduced that vanilla could be grown on plantations elsewhere.