The fine structure of the guard cells of helianthus annuus

Abstract

The guard cells of Hellanthus annuus contain elements of endoplasmic reticulum and large numbers of mitochondria and dictyosomes. Each guard cell possesses a complex system of small to large vacuoles which contain small, membrane-bound vesicles; the vacuole may actually be one highly invaginated and dissected vacuole extending throughout the cell, A highly developed grana fretwork within the plastlds implies full photosynthetic capability and the capability of producing the osmoticulum required for turgor change. No plasmodesmata occur between the sister guard cells or between the guard and epidermal cells, It is postulated that there is a close relationship between plastid development and the presence or absence of plasmodesmata. No microbodies were positively identified in any of the guard cells. Microtubules appear to lie in two planes, thereby giving support to the "two system" observation for microtubules in the guard cells of Pisum sativum.