Stipule (redirected from stipular)

stipule [′stip·yül]

(botany)

Either of a pair of appendages that are often present at the base of the petiole of a leaf.

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Stipule 

either of a pair of lateral appendages at the base of a leaf. The stipules infrequently fuse with the leaf stalk and with each other. Many plants lack stipules. At the base of the leaf stalks of compound leaves there are analogous formations called stipels (for example, in beans). Stipules are generally small, but they are large in vetchling, peas, and violets. In some plants, such as bedstraw and Asperula, they resemble leaves; in others, such as the locust, they do not. Stipules often play a protective role. By fusing together and embracing the stem, they form a funnellike opening (in buckwheat and sorrel) that protects young leaves. In the buds of many plants the stipules partially cover the young leaves (oak, linden, elm) and fall after the leaf unfolds.