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On the fine structure of the liquid producing floral gland of the orchid, Coryanthes speciosa
Author(s) -
Schnepf Eberhard,
Deichgräber Gisela,
Barthlott Wilhelm
Publication year - 1983
Publication title -
nordic journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.333
H-Index - 33
eISSN - 1756-1051
pISSN - 0107-055X
DOI - 10.1111/j.1756-1051.1983.tb01457.x
Subject(s) - mucilage , biology , vesicle , granule (geology) , secretion , biophysics , membrane , cell wall , homogeneous , botany , sugar , microbiology and biotechnology , anatomy , biochemistry , paleontology , physics , thermodynamics
The flowers of the “bucket–orchid”, Coryanthes speciosa , have two finger–like glands on each side of the column. They secrete large amounts of an aqueous fluid which drips into a bucket–like part of the labellum, the epichile. The fluid contains low amounts of sugars (glucose, fructose, saccharose, mannose), of ions, of a polysaccharide mucilage and unknown substances which provide odour and taste. The fluid seems to be discharged from the epithelial cells of the gland. They contain many dictyosomes, a well developed ER, occurring mainly as smooth, tubular interconnected elements, and coated pits at the plasmalemma as well as coated vesicles at the cell periphery and around the dictyosomes. Especially in young glands, the coated pits are frequently associated with lumps of osmiophilic material at the outer surface of the plasmalemma which are. however, observed also independent of coaled pits. The cuticle consists of an outer, homogeneous layer and an irregular, inner one. The latter is interspersed with a network of fibrils which merge into a mucilage that fills a voluminous subcuticular space in active plants. It is assumed that water secretion is the consequence of mucilage discharge and that the cuticle functions as a filter. The ER seems to supply the dictyosomes with membrane material. It is possible that the coated pits recycle membranes; an exocytotic function, however, cannot be excluded.