Nature News: Red maple buds enjoying the last days of dormancy before budburst

I have a bad habit of always looking to the future, winter isn’t over yet but I’ve found myself starting to think about signs of spring to come. 

As an exercise in centering myself in the here and now, especially since we are finally in the middle of a beautiful snowy winter, I wandered around my backyard appreciating what the woods had to offer. I found animal tracks and hemlocks still encased in ice. The waterfall, covered with a blanket of snow, could be heard gurgling underneath and river ice cracked and boomed. A hint of color, in addition to the green conifers, was provided by the brilliant red buds of the red maple trees.   

Red maple buds as they appear this week, in late February, in Maine. Dormant and waiting for the longer, warmer days of spring to burst. Sue Pike Photo

Project Budburst is a great way to get involved in citizen science!

Last March, I started a three-month bud-watch project with my students in an attempt to get them outside, doing science as we plunged into remote learning. I participated as well. I found a beautiful young red maple tree with some bright red buds dangling at eye level and decided to follow those, entering weekly information about the state of the buds into an online citizen science database called Project Budburst (budburst.org). While doing this, I felt like I really got to know this tree. I even (rather uncreatively) named one particular bud “Red” and another “Rosie.” So, I visited Red and Rosie Jr. (new buds on the same twig) this past week to see how they were getting on.  

They were both there, chilling out in the wintry weather. I could count the number of rings around the twig that are the remnants of previous years’ terminal buds (the buds like Red and Rosie that emerge from the tip of the twig). Using these rings, I was able to figure out that the twig itself was about three years old and also see where this twig had added about an inch of new growth to where the buds formed last year.   

I had recently read an article (“The Sex Life of the Red Maple” by Richard Primack of Harvard’s Arnold Arboretum) that got me wondering what gender these buds actually are.

 Red maples usually have all male or all female flowers, but some are a mix of both (called perfect flowers) and sometimes a supposedly all-male tree will produce fruit.  Last spring when I named them, I was more focused on when these buds were breaking (opening up) than considering their gender. So I checked my photos of the buds in flower from last year and found that both Red and Rosie were male flowers with the characteristic stamen composed of a long, thin filament supporting the anther – a narrow disk that contains the pollen. This doesn’t mean the whole tree is male. Red maples are notorious for not following strict gender roles. I’m looking forward to checking later this spring to see if these still are producing male flowers or whether they’ve switched to female flowers.

The same buds as above–Red is top left, Rosie is lower right–at the end of last April (2020). You can tell that the buds that have flowers aer males by the long stamen composed of a thin filament and pollen-carrying disk-shaped anther. Sue Pike Photo

But, bud burst will happen later; right now, the buds are still dormant. 

Buds are wonderful structures, resilient little capsules that surround and protect the embryonic flowers and leaves. The outer part is actually made of modified leaves, called bud scales, that are tough enough to keep out insect pests and also help insulate the inner tissues. These buds formed last fall at the end of the growing season when the trees had enough food and energy to make the buds. This is a critical strategy for overwintering. Trees can’t wait until the spring to make these structures – they won’t have enough leaves and there isn’t enough light. So instead, in the fall everything the tree needs to flower and reproduce, to form its first leaves and start to photosynthesize, is packed inside those tiny buds, dormant now, waiting for warmer and longer days to burst into new growth.

I like to think that, like me, those nascent flowers and leaves are cozily wrapped up in their buds, enjoying the lazy days of winter while dreaming about spring.

Published February 24, 2021 in seacoastonline.com, the York Weekly, Fosters’ Daily & the Portsmouth Herald.