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Anatomical and physiological characteristics of the petiole of Abutilon theophrasti in relation to circadian leaf movements
Author(s) -
Fuhrman Margaret H.,
Koukkari Willard L.
Publication year - 1981
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1981.tb04483.x
Subject(s) - abutilon , petiole (insect anatomy) , pith , biology , circadian rhythm , lamina , darkness , botany , cortex (anatomy) , anatomy , neuroscience , hymenoptera , weed
Leaf movements in Abutilon theophrasti Medic, were monitored manually and by a continuous electronic recording device. Plants entrained to a daily regime of a 15 h light span followed by 9 h of darkness showed rhythmic movements that persisted under conditions of continuous illumination and constant temperature with a circadian period. The rhythmic change in orientation of the leaf from a near horizontal (day) to a near vertical (night) position was attributed to movement of the blade and not the petiole. The end of the petiole next to the blade functions as a joint or pulvinus. Anatomical confirmation of the existence of a pulvinus in the Abutilon leaf was provided by light microscopy. Vascular tissue in this region forms a solid cylinder with no pith, and the cortex is parenchymatous. In the main part of the petiole, the vascular tissue is arranged in four to six bundles, a pith is present, and the cortex contains a sub‐epidermal ring of collenchyma. Both the functional and anatomical evidence indicate the presence of a pulvinus that functions in circadian leaf movements of Abutilon.