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Sieve‐element characters of Myristicaceae: Nuclear crystals, S‐and P‐type plastids, nacreous walls
Author(s) -
Behnke H.Dietmar
Publication year - 1991
Publication title -
nordic journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.333
H-Index - 33
eISSN - 1756-1051
pISSN - 0107-055X
DOI - 10.1111/j.1756-1051.1991.tb01413.x
Subject(s) - plastid , phloem , biology , sieve tube element , sieve (category theory) , botany , parenchyma , biophysics , biochemistry , chloroplast , mathematics , combinatorics , gene
The phloem of the Myristicaceae is composed of sieve elements, parenchymatous cells, and fibers. Within the metaphloem and secondary phloem parenchymatic layers including prominent secretory elements alternate with tangential bands of fibers and layers composed of sieve elements, companion cells and phloem‐parenchyma cells. among the latter the sieve elements are most abundant and easily identified by the presence of thick (nacreous) walls. The most characteristic feature of the sieve elements of Myristicaceae (and found nowhere else among the Magnoliiflorae) are nuclear crystals, which are released into the lumen during nuclear degeneration and persist in the mature cell. P‐and S‐type sieve‐element plastids were recorded for the 18 species investigated. Both types of the plastid are characterized by large diameters and many medium‐sized starch grains. The sizes and contents (small protein crystals only) of the P‐type plastids of the Myristicaceae do not conform to the tiny P‐type plastids (with large protein crystals) of the Annonaceae, a family to which the Myristicaceae is traditionally allied.