A Histological and Structural Study of Phacelia tanacetifolia Endosperm in Developing, Mature, and Germinating Seed

The ruminate endosperm of developing, mature, and germinated seed of Phacelia tanacetifolia was investigated with light and scanning electron microscopy and energy dispersive spectroscopy. At each of the three stages examined, large numbers of calcium oxalate crystals were visible in the endosperm epidermis and in a few cells of the outermost endosperm layers. In developing seeds the endosperm cells were characterized by a large number of starch grains interspersed with some protein bodies of small size, while in the mature seeds, there were few small starch grains and a large number of big protein bodies. The globoids observed within protein bodies could be ascribed to the "type 1" phytin inclusions and showed considerable P and Ca levels, some K, and only traces of Mg and S. During germination we observed vacuolation and initial digestion of the protein bodies, which was indicated by peripheral pitting. Digestion started from the endosperm epidermis and continued toward the inner endosperm. The Ca conta...