What Are Those Bumps on My Star Magnolia? Are They Seed Pods?

This Bump Is More Than a Bump, but Not Poisonous

Seed pod of star magnolia tree with orange seeds popping out.
Before the orange seeds start to burst out, a star magnolia pod just looks like a "bump.". David Beaulieu

Have you ever wondered what all those light green bumpy growths are that show up on your star magnolia tree (Magnolia stellata) in late summer? They might look like mere bumps -- weird growths that may cause a novice to think that the tree has a problem -- but they're not.

Those bumps are actually star magnolia seed pods. In the picture, taken in September in a USDA plant hardiness zone 5 landscape, the orange seeds have already begun to burst out, helping us to identify the bump as a seed pod.

But as long as the star magnolia seeds remained inside, the pod appeared to be little more than a curious, amorphous mass. According to the Penn State Extension, wild birds eat the seeds, benefiting from "their high fat content."

Incidentally, the bumps on some plants truly are growths, not seed pods. You can see a picture of a plant "gall" on an azalea bush here.

What Do Southern Magnolia Seed Pods Look Like? Are They Poisonous?

Of course, other types of magnolia trees also have seed pods, and they can look quite different from those on a star magnolia tree. Here is a picture showing what the seed pod on a Southern magnolia (Magnolia grandiflora) looks like. That is what is left over after the large, fragrant flowers of the tree pass by and the contents of the pod mature.

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.

Wildlife (including wild birds and squirrels) eats the seeds. According to the Washington State University Extension, the seeds of Southern magnolia are poisonous if eaten by humans (the wild birds and the squirrels do not seem to be adversely affected). CatHelp-Online lists M. grandiflora as being poisonous for cats; while toxicity information is hard to find regarding dogs eating the seeds, it is always better to err on the side of caution.

Star magnolia seeds, by contrast, are not toxic to humans, if we are to believe the University of California, Davis website. Nor, according to the ASPCA, are they poisonous to pets (either cats or dogs).

Can You Start a New Magnolia Tree From Seed?

You sure can. 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:

  1. It will take a long time for the plant to make the journey from seedling to flowering tree.
  2. If you want to collect the seeds, yourself and take over the propagation process from Mother Nature, you will not get far unless you keep in mind a trick employed by horticulturists.

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:

  1. Wait for the pods (cones) to open (that is, do not force the seeds out prematurely), but do not wait too long (it's bad to have the seeds dry out completely while still in the pod).
  1. Soften the orange outer coating on the seeds by soaking them in water for several days.
  2. Wash off the now-loosened coating using soapy water.
  3. Lay out the seeds to dry a bit overnight.
  4. Put the magnolia seeds in a sealable plastic baggie filled with moistened peat moss.
  5. "Stratify" the seeds. That is, put the baggie in the refrigerator "for at least 60 days." It is through this "stratification" (subjecting the seeds to the cold) that you get the seeds ready to germinate.
  6. In spring, take the baggie out of the refrigerator. Spread the contents (both peat moss and seeds) onto a seeding tray, and keep them where it will be 70-75 degrees Fahrenheit. 
  7. Keep the peat moss moist, but not soggy.
  8. At germination (which should take "five to 14 days"), transplant the seedlings into pots that have been filled with a potting mix.
  1. Put the pots in a South-facing window and keep the potting mix moist, but not soggy.
  2. Transplant the seedling outdoors once all risk of frost is over.