The veins of a leaf are the vascular bundles, collections of xylem and phloem Plant Growth Primary Growth versus Secondary Growth - Primary growth is growth in the length of a plant whereas secondary growth refer to an growth resulting in an increase in diameter. For a picture of primary tissues in a young dicot stem with labels, click here . Secondary phloem is the secondary growth tissue that conducts food that the plant makes from the leaves to the rest of the plant. The cork cambium is involved in producing the tough, thick covering of a stem and root. To see secondary xylem and secondary phloem, click here .
Secondary xylem is the wood of a tree trunk.
The annual rings are created by alternating bands of summer wood cells and spring wood cells. The summer wood cells are smaller in diameter, due to less available water, while the spring cells are larger in diameter due to rapid growth from more abundant water. To see secondary xylem and the corresponding annual rings, click here .