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SCANNING ELECTRON MICROSCOPY AND ENERGY DISPERSIVE X‐RAY ANALYSIS OF CHALK SECRETING LEAF GLANDS OF OF PLUMBAGO CAPENSIS
Author(s) -
Sakai William S.
Publication year - 1974
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1974.tb06032.x
Subject(s) - magnesium , scanning electron microscope , calcium , biology , electron microscope , calcite , microscopy , silicon , potassium , biophysics , mineralogy , materials science , chemistry , optics , metallurgy , composite material , paleontology , physics
Chalk secreting leaf glands of Plumbago capensis Thunb. were examined by polarized reflected light microscopy, scanning electron microscopy, x‐ray diffraction, and energy dispersive x‐ray analysis. There are about 23 glands per mm 2 on the lower leaf surface and none on the upper surface. Each gland measures 20–30 μm in diam and consists of four small secretory cells surrounded by four subsidiary cells. Secretion of chalk is apparently through a pore in the surface of each secretory cell. The secreted material was crystalline and x‐ray diffraction confirmed the presence of two minerals: calcite (CaCO 3 ) and nesquehonite (MgCO 3 · 3H 2 O). Energy dispersive x‐ray analysis revealed the presence of magnesium, silicon, phosphorus, sulfur, chlorine, potassium, and calcium in the epidermal cells. However, only calcium and magnesium and traces of silicon were detected in the secreted material. A distribution analysis showed calcium and magnesium to be uniformly distributed through the secreted material.