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DEVELOPMENTAL PATTERNS IN STEM PRIMARY XYLEM OF WOODY RANALES. II. SPECIES WITH TRILACUNAR AND MULTILACUNAR NODES
Author(s) -
Benzing David H.
Publication year - 1967
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.1537-2197.1967.tb10704.x
Subject(s) - phyllotaxis , biology , botany , xylem , gymnosperm , taxon , woody plant , evolutionary biology , shoot , meristem
Patterns of early protoxylem strands in vegetative stems of 16 species of woody Ranales representing nine families with trilacunar or multilacunar nodes are illustrated and discussed. The order of differentiation of first protoxylem in all examined species is basipetal. Open, protoxylem strand patterns are more common than closed patterns in these taxa and 11 other woody ranalean species with unilacunar nodes. Protoxylem strand patterns in woody Ranales are diverse, even among species with identical phyllotaxis and nodal anatomy. Pattern similarities of possible taxonomic significance exist, however, between some species of the Annonaceae and Myristicaceae, Hernandiaceae and Lauraceae, and the Canellaceae and Winteraceae. The general diversity of strand patterns in woody Ranales may reflect the high degree of evolutionary isolation among ranalean families. Results of these investigations on stem anatomy of woody Ranales indicate that the two‐trace, unilacunar node is probably not primitive in the Angiospermae. Evidence from this study and others suggests that the primitive node in the Angiospermae, and possibly in all seed plants, is one‐trace, unilacunar or trilacunar. Two‐trace, unilacunar nodal anatomy of the Clerodendron type may have evolved in conjunction with the evolution of decussate phyllotaxis. The protoxylem strand patterns of Illicium and/or Drimys are probably the most primitive of those described in the woody Ranales.