An editor reads books. A mathematician reads numbers. A doctor reads x-rays. A botanist reads…..TWIGS!
On Saturday, several Boston area teachers became botanists for the morning. Michael Dosmann, Curator of Living Collections, taught teachers how to interpret the bumps, shapes, and nicks on a twig.
The variety of terminal buds alone makes for interesting reading. Each bud is protected by bud scales, which are modified leaves that completely cover the delicate tissue, and prevent winter’s ill effects. There are the rubbery, smooth duckbill of the tulip tree; the large, sticky bulb of the horse chestnut; the fuzzy cap of the magnolia; the sharp, slender spear of the beech; the clustered crown points of the maple; and the deer hooves of the katsura tree. Moving further back from the terminal bud, one may find lateral buds, sometimes in opposite arrangement on the twig, and sometimes alternating along its length. Teachers learned that a bud contains all the parts for next season’s leaves, flowers, and stems. Wow!
Each lateral bud is preceded by a leaf scar—the place where the previous season’s leaf used to attach. Leaf scars are also distinctive, sometimes triangular, circular, or crescent shaped. Within those leaf scars one can glimpse tiny dots known as bundle scars. These are the ends of veins that transported food and water between leaf and twig. A strong twig reader can identify many tree species by decoding the combined clues of bud, arrangement, and leaf scars.
If you continue reading backwards from the terminal bud on the twig, you might find some rings that might resemble saggy socks in appearance. These growth rings, known as terminal bud scars, remain after the bud scales of the previous year’s terminal bud fall off. This section represents one year’s growth. By counting sections between growth rings, one can discover the age of that twig or branch.
Armed with this information, teachers went out into the landscape to practice newly gained twig reading skills. And as any teacher knows, the more we practice reading, the better (twig) readers we become!
Join the Arboretum for Educators on February 4.