Marigold flower parts. Light micrograph of a vertical section through a carpel or pistil (the female part) of a marsh marigold (Caltha palustris). The carpels are found in the central part of the marsh marigold flower. Here, the outer layer (light blue) is the ovary wall and the inside of the ovary is at centre. The ovary contains the ovules (two seen here). The ovule at left has been sectioned and is hanging down from the top of the ovary. The sectioning has revealed the central cavity, and the ovum (egg) in this cavity. This egg, when fertilised, is what develops into an embryo for a new plant, forming the centre of the plant's seed.