STRUCTURAL AND HISTOCHEMICAL CHARACTERS OF THE PROSOPIS TAMARUGO PHIL. SEED COAT, IN RELATION TO ITS HARDNESS

SUMMARY The structural and histochemical characteristics of the Prosopis tamarugo Phil. seed-coat have been investigated by bright-field, fluorescence and scanning electron microscopy. P. tamarugo seed dormancy is exclusively due to the hardness of the seed-coat. The water barrier is thought to be located in the superficial portion of the palisade cells named “cylindrical part”, sited directly under the cone-like endings of the palisade cells themselves. The periclinal disposition of the “cylindrical parts” originates a line particularly evidenced by histochemical procedures of fluorescence that indicate their lipidic nature. It is believed that under natural environmental conditions a process of cracking deeper than this level permits water entry.