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TRANSFER CELLS IN THE PLACENTAL PAD AND CARYOPSIS COAT OF PAPPOPHORUM SUBBULBOSUM ARECH. (POACEAE)
Author(s) -
Rost Thomas L.,
Artucio Primavera Izaguirre,
Risley Edward B.
Publication year - 1984
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.1537-2197.1984.tb14161.x
Subject(s) - caryopsis , vascular bundle , biology , ovule , aleurone , epidermis (zoology) , anatomy , coat , botany , germination , endosperm , pollen , paleontology
During caryopsis development the layers of the pericarp, integuments, and nucellus all contribute to the formation of the caryopsis coat. The coat consists of a layer of outer pericarp epidermal transfer cells, a collapsed and senescent layer of middle pericarp cells, and a discontinuous layer of inner pericarp epidermal transfer cells. The latter is not present across the placental pad. The integuments are present as a collapsed dense layer, the nucellus is discontinuous and cellular. The placental pad occurs at the ventral surface of the caryopsis, opposite the scutellum and coleorhiza. It consists of 15–20 collapsed cell layers, including the pigment strand and placental vascular bundle. From the inside several partially collapsed cell layers of the nucellar projection occur which contain transfer‐cell walls. The middle dense layers, the pigment strand, consist of the middle pericarp remnant, plus the remains of the placental vascular bundle. The pericarp inner epidermis does not extend across the pad. The aleurone layer is a continuous uniseriate layer around the entire caryopsis except at the placental pad; here it is crushed and contains the remnant of a transfer‐cell wall. The outer pericarp epidermis is a continuous layer of transfer cells across the pad. These cells contain membranous inclusions suggesting that they may be functional during germination.