Stomata on the Primary Root of Ceratonia siliqua

Anomocytic stomatal complexes observed with light and scanningelectron microscopes on the primary roots of Ceratonia siliqua(carob tree) are described. Stomata are randomly distributedthroughout the surface of the root zones which possess maturevascular tissues, i.e. from the zone of root hairs to the transitionzone. Stomatal orientation does not follow that of the rootepidermal cells whilst their distribution does not seem to forma regular pattern. Ceratonia siliqua, primary root, stomata     

On the Structure of Lettuce (Lactuca sativa L.) Endosperm during Germination

Endosperm cells of lettuce (Lactuca sativa L.) are characterizedby thick cell walls and dense cytoplasm which contains numerousprotein bodies. Other organelles such as nucleus, mitochondria,plastids and dictyosomes are typical of plant cells. Light andelectron microscopy reveal that before radicle emergence micropylarcells of endosperm tissue undergo drastic protoplast alterations.These alterations seem to be the only structural modificationsbefore rupturing of the tissue since the walls of the endospermcells seem to degrade only after radicle emergence. The differentialbehaviour of the micropylar area of the endosperm before radicleemergence and the observation that the micropylar cells remainmetabolically active long after radicle emergence while therest of the tissue is almost completely disintegrated, suggeststhat the endosperm cells of the micropylar area may have a roleother than being a main reserve site like the rest of the endosperm. Lactuca sativa L., endosperm structure, seed germination, lettuce