Biology Interview Question:

Do all vascular plants develop annual rings?

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Vascular plants are those, which have phloem and xylem structures within them to transport water and nutrients around the plant. Most of the plants you see around you are vascular. Think about grass or herbaceous plants - you will not find growth rings in those if you cut them through the middle.

Growth rings occur is plants with lignin in their stems (trees in other words). The rings are caused by the different rates of growth in summer and winter. In summer the tree grows quicker, the lignin fibers are less dense, and the ring is a bit lighter in color. In winter, growth is slower and the fibers are pack closer and appear darker.

Annual growth rings are near universal in the trees of the temperate regions. Trees growing in the tropics experience an even temperature environment over the year and rings are less pronounced or absent.
Submitted by: Administrator