Citrus Leaf Stomata: Structure, Composition, and Pore Size in Relation to Penetration of Liquids

Abstract

1. The stomatal pore in Washington navel orange leaves is elliptical in shape. The average stomatal pore lengths and widths for medium-sized leaves of Eureka lemon were 7.04 x 3.08 ~μ; of Marsh grapefruit, 8.06 x ~2.08 ~μ~; of Valencia orange, 8.91 x 3.80~ ~μ; and of Washington navel orange, 4.78 x 2.3~ ~μ.~ Stomatal pore length and width were both highly significantly different for each kind of leaf. 2. Study of a stoma of a lemon leaf shows that it has a complicated surface structure which makes calculation of the action of surface forces on spray liquids more difficult than if based on stomatal pore size alone. Evidence based on molecular forces indicates that citrus stomata are not penetrated by water but may be penetrated by oil.