Those bumps are actually star magnolia seed pods. As long as the star magnolia seeds remain inside, the pod appears to be little more than a curious, amorphous mass. But in late summer (September in USDA plant hardiness zone 5), the orange seeds begin to burst out, helping us to identify the bump as a seed pod. Wild birds eat the seeds, which are loaded with nutritious fat. Gardeners should not become complacent, though: The bumps on some plants truly are growths, not seed pods. An example is provided by the bumps that sometimes appear on azalea shrubs.
What Other Magnolia Seed Pods Look Like
Of course, other types of magnolia trees also have seed pods, and they can look quite different from those on a star magnolia tree. The red color of the seeds in Southern magnolia seed pods is just as striking as the orange color of the seeds borne on a star magnolia. Wild birds, squirrels, and other animals eat the seeds. Like star magnolias, closely related magnolias widely grown in Northern yards, such as Magnolia x soulangiana, are safe to grow around kids and pets.
Another Magnolia Family Member: the Tulip Tree
Tulip trees (Liriodendron tulipifera) are associated with magnolia trees through family ties, a connection easily detected if you inspect the flower. This wonderful shade tree has yellow fall foliage. The seeds are not colorful, being a drab tan.
How to Start a New Magnolia Tree From Seed
Gardeners who grow magnolia trees sometimes find that a seedling has sprouted in the landscape. If given the proper conditions, this seedling will eventually become a magnolia tree in its own right. You should keep a couple of warnings in mind, though:
It will take a long time for the plant to make the journey from seedling to a flowering tree. If you want to collect the seeds and take over the propagation process from Mother Nature, you will not get far unless you keep in mind a trick employed by horticulturists, a term that refers to those who study horticulture.
Regarding this second point, not all of the steps required to start a new magnolia tree from seed will be intuitive for beginners. Here is a summary of the propagation process as detailed by Stefan Cover via the International Dendrology Society:
