Premium
DIFFERENTIATION AND CONTINUITY OF THE PHLOEM IN THE LEAF INTERCALARY MERISTEM OF LOLIUM PERENNE
Author(s) -
Forde B. J.
Publication year - 1965
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.1537-2197.1965.tb07271.x
Subject(s) - meristem , biology , phloem , lolium perenne , lamina , botany , perennial plant , constriction , secondary constriction , anatomy , shoot , chromosome , biochemistry , gene , karyotype , endocrinology
Serial transverse sections of the stem tip and leaf bases of immature perennial ryegrass leaves were examined to assess the effect of the intercalary meristem on assimilate movement. The development of procambial strands in very young leaves was followed, and the subsequent differentiation of proto‐ and metaphloem examined in both lamina and sheath. In major bundles the first two or three series of protophloem cells differentiated acropetally into the leaf and they or their crushed remnants could be recognized at all levels. A further three or four series of protophloem cells differentiated basipetally, as did the protophloem of all minor bundles and the metaphloem. The basipetal differentiation of the bulk of the phloem combined with crushing of older cells resulted in acute constriction or even complete local blockage of the functional phloem in the active meristematic region. This constriction of the phloem would tend to divert assimilates into the dividing cells both from the stem below and from the mature upper portion of the leaf. No constriction was found at the base of a mature sheath.