Stems

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Stems

"...that thing that comes up from the ground that the leaves attach to"

Stems are the above-ground structures that bear the plant’s leaves and flowers. The stem provides a host of services to the plant:

It provides a pathway for transporting water up to the leaves, and moving the sugars produced in the leaves down to nourish the roots.
It acts as a sturdy mast to hold up the leaves and help orient them for maximum exposure to sunlight.
It can act as a storage site for carbohydrates.

All stems have nodes along their length. A node is the point at which a leaf attaches to a stem. Small buds called axillary buds occur at nodes, typically just above where the leaf meets the stem (the leaf axil). These buds may sprout to form new leaves or side shoots. The very tip of the stem where the most rapid growth usually occurs is called the apical bud (apex=highest point).

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Many familiar garden plants’ stems are soft and green; these are called herbaceous (her-BAY-shus) stems. Examples include the stems of annuals like impatiens and lettuce, and perennials such as hostas and lupines. The stems of trees and shrubs also start out soft and green, but become woody as they mature.

Stems contain vascular tissues—the "circulatory system" of the plant. Similar to our blood vessels, vascular tissues form an intricate network of veins that carry fluids throughout the plant. Large cells of the xylem (ZY-lem; Gr. xylon=wood) form a conduit for transporting water up from the roots; the smaller cells of the phloem (FLOW-em; Gr. phloos=bark) transport sugars produced in the leaves.

In herbaceous stems, the xylem and phloem are contained in vascular bundles.

Herbaceous stem cross-section

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A plant’s shoot system consists of its above-ground stems, plus any branches and leaves.

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Handle with Care
When transplanting tender seedlings, you should always grasp them by their leaves, not their stems. If a leaf is damaged, the plant can replace it; if the main stem is damaged, it can’t be replaced.

Digging Deeper

Buds and Sprouts
On some plants, such as philodendron, the axillary buds are small and may not be easily visible. But if you examine the vines, you’ll probably see places where a side branch has arisen from an axillary bud at a node. And if you prune one of the vines back to a node, you’ll likely find a side shoot forming within a few weeks.

The axillary buds on tomato and coleus sprout freely, and you’ll often see shoots arising in the leaf axils. If you’ve ever pruned "suckers" off your tomato plants, you’ve removed shoots that have arisen from axillary buds.