Anatomy and development of the superficial layers in stolons of white clover (Trifolium repensL.)

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Abstract Scanning and transrrussion electron microscopy, together with bright field and fluorescence microscopy, were used to examine the cuticle, epidermis, hypodermis, and cork cambium (phellogen) of white clover (Trifolium repens L.) stolons during growth and maturation. Development of the hypodermis included the deposition of a suberin lamella in the cell walls. No suberin was deposited in the cell walls of the epidermis. The cork cambium was formed in the third to fifth internodes basipetal to the stolon apex, and produced layers of suberised cork cells (phellem) when internodes were 11 to 14 basipetal to the apex. Breakdown of the cuticle began at a very early stage. Bacteria were seen to colonise the cuticle and apparently lyse the cuticle and epidermal cell walls and penetrate eventually into the hypodermis. The suberin lamella appeared to be more resistant to bacterial attack than the cellulose portion of the cell wall. It was concluded that variation in the degree of breakdown of the cuticle was probably responsible for the large variation in phosphate absorption of stolon internodes previously observed.