SIEVE-ELEMENT CHARACTERS OF THE PROTEACEAE AND ELAEAGNACEAE - NUCLEAR-CRYSTALS, PHLOEM PROTEINS AND SIEVE-ELEMENT PLASTIDS

The sieve-element characters of 34 species from the Proteaceae and Ela eagnaceae have been studied by transmission electron microscopy. While nondispersive protein bodies and dispersive P-protein are typical com ponents of both families, specific forms and/or their distinctive orig in accentuate some taxa. Within the Grevilloideae, subfamily of Protea ceae, a number of Australian species and genera contain protein crysta ls of nuclear origin arranged into rosette-like bodies, while in the o ther members studied from the same subfamily no nondispersive protein bodies were found. Several Australian and South African genera of the Proteoideae contain compound-spherical nondispersive protein bodies th at reside in the cytoplasm from their very beginning. In the Elaeagnac eae three different P-protein bodies are present of which one is tubul ar and dispersing, another is nondispersive and of irregular-stellate form, and a third is globular (resembling a P-protein from Cucurbita). The great majority of the species studied from the Proteaceae contain s form-Ss sieve-element plastids, Lomatia ilicifolia and Macadamia ter nifolia are distinct in having form-Pcs plastids. The average diameter of stem sieve-element plastids in the family is 1.38 mu m. The Elaeag naceae (three species investigated) is a pure form-So family (average diameter: 0.8 mu m). There are no specific sieve-element characters th at would support any relationship between the Proteaceae and Elaeagnac eae. While affinities of the former to pre-Gondwanan parts of the Rosa nae/Myrtanae are discussed, a reconsideration of the Elaeagnaceae as a possible member of the Violanae (identical features with Cucurbitacea e) is proposed.