Lidia ADUMITRESEI
“Anastasie Fatu” Botanical Garden, “Alexandru
Ioan Cuza” University of Iasi,
Dumbrava Rosie Street no. 7-9, 700487 Iasi – Romania
Irina Neta GOSTIN
“Alexandru Ioan Cuza” University of Iasi, Biology
Department, 20 A Bulevardul Carol I, 700505 Iasi – Romania
https://doi.org/10.47743/jpd.2025.32.1.982
Keywords: anatomy, earlywood, latewood, perennial
stem, ring-porous species, Rosa spp.
Abstract: The observations comprise a comparative
study of the anatomical structure of the perennial stem in the
species Rosa canina L., R. damascena Mill.,
R. rubiginosa L., and R. rugosa Thunb., cultivated
in the Botanical Garden of Iasi.
Cambial activity gives rise to a relatively thin outer ring of
secondary phloem and to several rings of secondary xylem, which
indicate the age of the examined branch. Within the phloem ring,
conducting elements (sieve tubes and companion cells), phloem
parenchyma cells (some containing idioblasts), and irregularly
dispersed libriform fibres with thickened, lignified walls can
be distinguished, these fibres being more abundant in R. rugosa.
In R. rubiginosa, the phloem fibres are arranged in two
layers separated by phloem parenchyma. At the periphery of the
phloem ring, in contact with the inner layers of the primary cortex,
thick bands of sclerenchymatous fibres with very thick, heavily
lignified walls (with a punctiform lumen) are visible, especially
in R. canina and R. damascena.
Analysis of the secondary xylem shows its ring-porous aspect in
all observed species. Each growth ring displays on its inner side
vessels of larger diameter (representing the earlywood), separated
by libriform fibres with strongly thickened, intensely lignified
walls. On the outer side, each ring contains fewer vessels of
smaller diameter, with libriform fibres predominating –
a feature common to all examined species. In contact with the
pith, remnants of the primary xylem can still be observed, completely
lignified and protruding as small bundles into the pith.
All annual rings of secondary xylem are traversed by numerous
multiseriate medullary rays, usually of uniform width or variable
in R. canina. In all cases, the rays consist of radially
elongated cells with relatively thin but lignified walls. In all
species, the oldest ring of secondary xylem is thicker than the
subsequent ones, in which large-diameter vessels predominate.
The pith exhibits a network-like appearance, in which very large,
thin-walled parenchyma cells are separated by much smaller cells
with moderately thickened but strongly lignified walls.
How to cite this article:
ADUMITRESEI L. & GOSTIN I. N. 2025. Anatomical structure of
the perennial stem in different Rosa L. species. J.
Plant Develop. 32: 19-25.
https://doi.org/10.47743/jpd.2025.32.1.982
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