On my springtime strolls through the neighbourhood with my dog, I have been noticing many explosions of yellow. Our family had one of these bushes in our backyard. But more than their flowers, the thing I remember about them was their bark, which was covered in little bumps. When I was a kid, this really bugged me for some reason, which may or may not say something about my personality. I thought that maybe little insects hid in them, like galls. I would scrape off the bumps but never found any insects. Finally, all these years later, I've decided to scratch that mental itch of what those things are.
By any other name
Forsythia, I have since found out, is the genus of flowering plants comprising of thirteen species and some hybrids in the olive family, mostly native to eastern Asia. It was named after William Forsyth. Another thing that bugs me is a scientific name based on a person, because then it doesn't give you any hints about the group itself. However, he was a royal head gardener and founding member of the Royal Horticultural Society, so I guess he was deserving of some recognition.
Anyway, back to the bumps. The short answer is that they are called lenticels, which are openings for gas exchange in the woody stems of these plants. They are openings for the exchange of gases, like our nose and mouth. Leaves have openings called stomata. So other plants have lenticels, but not always so conspicuously. The lines on birch bark and cherry trees, another thing I have wondered about, are also lenticels. And the specks on the surface of apples and pears are lenticels.
Reasons to be
But why do Forsythia have so many lenticels? I couldn't find an answer. It might be that it is a bad question. It might be that Forsythia do not really have more than other plants. But I couldn't find data on that. So I will suppose that they do have a lot of lenticels and speculate on why.
Some species of Forsythia have green stems. So they probably have chlorophyll in the bark and need these openings to exchange the gases. If this were a primitive state, then maybe the ones without stems still have the lenticels as leftovers. Also, their flowers come out in great abundance before the leaves. Maybe they need the lenticels for the gas exchange before the leaves come out.
I look forward to hearing from people who know something about botany to share some insights on this question. In the meantime, enjoy the flowers!