FURTHER-STUDIES OF THE SIEVE-ELEMENT PLASTIDS OF THE CARYOPHYLLALES INCLUDING BARBEUIA, CORRIGIOLA, LYALLIA, MICROTEA, SARCOBATUS, AND TELEPHIUM

The sieve-element plastids of 69 species of the Caryophyllales were in vestigate by transmission electron microscopy. All contained the speci fic subtype-P 3 plastids characterized by a peripheral ring of protein filaments. The presence or absence of an additional central protein c rystal and their shape being either polygonal or globular as well as t he average sizes of the sieve-element plastids are useful features in the characterization of some families. - Barbeuia contains sieve-eleme nt plastids that confirm its placement within the Phytolaccaceae. Lyal lia differs from Hectorella by including small starch grains in their sieve-element plastids, which otherwise by their globular crystals neg ate a closer connection to the Caryophyllaceae. The lack of a central protein crystal in its form-P3fs plastids places Microtea best within the Chenopodiaceae. Sarcobatus, a so far uncontested member of the Che nopodiaceae, contains form-P3cf plastids, i.e., including a central cr ystal not found elsewhere in this family. Telephium and Corrigiola, sh ifted back and forth between Molluginaceae and Caryophyllaceae, have f orm-P3cf(s) plastids with a polygonal crystal which favor their placem ent within the Caryophyllaceae.