Calla lilies are members of a large family of plants known as angiosperms. These are plants that use flowers, which contain separate male and female organs to reproduce. Once fertilised, calla lilies then produce seeds to continue the life cycle of the plant.
The life cycle of a calla lily starts with a seed, which contains genetic material that, under the right conditions, including sufficient water, soil and light, will germinate and grow to form a calla lily plant. Calla lily seeds are brown, oval-shaped, slightly bumpy and around 2mm (1/8 inch) in diameter, on average.
At first, calla lily seedlings use stored energy inside the seed to grow. Soon after, roots develop, drawing both nutrients and water from the ground. The plant uses these to continue to grow, forming leaves and stems that carry on photosynthesis, which continues to convert the nutrients and water into energy for more growth.
When the calla lily plant is mature, it will reproduce by forming a yellow, spikelike growth, called a spadix, that holds tiny flowers. The spadix is surrounded by a large, white and slightly ruffled sheath, or spathe, that forms from a leafless stalk. Pollen from the male reproductive organ, known as the anther, on the spadix flowers is transferred by insect or wind to the pistil, the female organ in the flowers.
When pollen touches the end of the pistil, called the stigma, it sticks to it. Sperm cells in the pollen then enter through the stigma down into the ovary. There, the sperm fertilises ovules in the ovary. The ovules will then grow into seeds and the ovary will turn into a seed pod. The spathe of the flower then dies back.
The seed pod of the calla lily forms a cluster of small, warty, green fruits. As they continue to grow, the seeds within the seed pod mature. When ripe, each dried fruit opens to spread the seeds. If the soil, water and light conditions are right, the seeds will then germinate, continuing the life cycle of the calla lily plant.