A flowering stem of Primula florindae at the stage of seed development, partially dissected.The picture shows phyllody - the process whereby the normal development of flowers is disrupted, giving rise to leaves. This can produce "green" flowers; e.g. by roses when each petal develops as a leaf.Here, some of the flower primordia in the centre of the inflorescence have developed into a single leaf. Normal flowers are borne on a pedicel (flower stalk, here cream, and later green). By contrast the leaves are borne on petioles ( leaf stalks ), which are reddish in hue here.The cause of a particular example of phyllody is difficult to determine. It may be due to environmental (climatic) factors. Many cases arise from infection by mycoplasmas - small pleiomorphic bacteria (in plants known as phytoplasmas). Such factors can alter plant hormone levels, resulting in developmental abnormality.