Some types of orchid are non-photosynthetic; others only produce chlorophyll when they have grown past the seedling stage. In all cases, the plant depends on sugars derived from a fungal partner for at least part of its life. The minute orchid seeds, with negligible nutrient reserves, will not germinate unless a fungus infects them, although the seeds can germinate aseptically if supplied with the 'fungal sugar' trehalose.