Botanicheskii zhurnal. 2016 101(6): 671–689
© N. V. Lavrentyev, O. V. Yakovleva
PERICARP AND SEED COAT STRUCTURE IN QUERCUS SPECIES (FAGACEAE)
GROWN IN THE BOTANICAL GARDEN OF ST. PETERSBURG
Komarov Botanical Institute RAS
197376, Prof. Popova Str., 2, St. Petersburg, Russian Federation
Phone +7 (812) 372-54-66
E-mail: [email protected]
SUMMARY
The results of anatomical study of pericarp and seed coat of Quercus species grown in
the Botanical Garden in St. Petersburg are presented for the first time. Eight Quercus species
from 3 sections and 7 subsections of the subgenus Euquercus were studied: Q. castaneifolia, Q.
macranthera, Q. mongolica, Q. robur, Q. alba, Q. imbricaria, Q. rubra, Q. coccinea. For the
first time, 2 kinds of sclereids were found in pericarp: with thickened and with relatively thin
cell walls. Thick-walled sclereids were localized in exocarp of the studied species as a whole
layer, and in mesocarp as groups of cells and single cells. Thin-walled sclereids were found in
the mesocarp. Using longitudinal, tangential and radial sectioning, the shape of large exocarpial
sclereids was determined to be irregular. Sclereid layer in the exocarp consisted of 3 cell types:
small sclereids with crystals, large irregular-shaped sclereids, and rounded sclereids. The
question of origin of sclereid layer and referring it to a certain anatomic zone (exocarp or
mesocarp) is still unanswered. Crystals of 2 shapes were found in the pericarp of studied species:
single rhomboid crystals and druses. The pericarp structure differs in species from both different
sections and different subsections; however, no specific anatomical features were revealed to
characterize the sections of Quercus. The main differences between species are: the cuticle
thickness; number of crystal-containing sclereids in the first row of exocarp sclereid layer;
presence or absence of pores; narrow or wide cavities in exocarp sclereids; the structure of
internal row sclereids in exocarp, and the boundary between exo- and mesocarp. Some interspecies differences were discovered in the mesocarp structure. They are: the contents of
parenchyma cells, distribution of large thin-walled non-obliterated cells, number and localization
of sclereid groups or single sclereids or their absence, druse occurrence in some cells. The
endocarp is weakly manifested in the studied species, though some species differ by prerence /
absence and character of pubescence. It was also established that species hardly recognizable by
morphological characters when grown under introduction, can be distinguished by anatomical
structure of pericarp. No significant species differences were revealed in the seed coat structure.
K e y w o r d s : Quercus, acorn, pericarp, seed coat, sclereids, anatomy, introduction.