Fig. 35.—Cross section
of a Sycamore bud. (× 7.)
When all the scales have been removed, there remains a tiny tuft of delicate green foliage leaves surrounded by a little down. Each leaf is folded fanwise, both for convenience of packing, and to protect its tender tissues from the cold and the damp when the bud is expanding. The complicated folding of these leaves is well shown in [Fig. 35], which is a magnified sketch of a cross section through a sycamore bud. The large sheaths surrounding the young leaves are four of the overlapping scales. In a large terminal bud a bunch of green flowers may often be found.
The bursting of the buds.—About the middle of April the tree wakens to new life. The stored food makes its way to the terminal buds; invigorated by the rich sugary sap the young leaves swell and push forward, burst apart the scales, and open out their folds to the light and air, as if eager to get to work at the earliest possible moment. The scales fall off to the ground, leaving close-set rings of scars; the growing point elongates, and new leaves—which were indistinguishable in the bud—grow out and expand. During the summer, food is plentiful, and a little bud appears in the axil of every leaf. Only with the autumn does the activity of the tree slow down. Except for some two pairs at the tip, the newest leaves now remain stunted. They form scales and close round the tender growing point protectingly, in readiness for the winter.
Fig. 36.—Sycamore twig in winter. (× ⅛.)
If necessary, the axillary buds could have behaved as the terminal bud did, in which case they would have grown out into side twigs. They usually remain small, however, until next year ([Fig. 36]), for the leaves are so busy making food, and the terminal bud is so busy growing in length, that no energy can be spared for their further development. If any accident had befallen the terminal growing point, one or more of the axillary buds would have grown out into side twigs. Gardeners take advantage of such reserve buds when they clip off the ends of twigs to make a plant grow “bushy.”