The Floral Nectary of Digitalis purpurea L., Structure and Nectar Secretion

Authors: GAFFAL K.P.¹; HEIMLER W.²; EL-GAMMAL S.³

Source: Annals of Botany, Volume 81, Number 2, February 1998 , pp. 251-262(12)

Publisher: Academic Press

Abstract:

The floral nectary of the foxglove (Digitalis purpurea L.), located at the base of the ovary, was examined by: scanning electron microscopy; quantitative bright-field microscopy via computer-aided 3-D reconstruction from serial sections; morphometric procedures; transmission electron microscopy and measurement of nectar efflux under different experimental conditions. Time-lapse video recording via a microscope with incident light clearly showed that the nectar escaped from the apertures of modified stomata. The volume flux via individual stomatal apertures was 0.31?0.1 nl min-1; therefore only a fraction of the total number of stomata per nectary (115?8) would be sufficient to discharge the amount of nectar reported in previous publications. The stomatal apertures are continuous with intercellular spaces traversing the small-celled nectariferous tissue. The latter is vascularized only by phloem, whose termini consists of rows of slender cells. These sieve-like cells are surrounded by more or less isodiametrical sheath cells with dimensions similar to the secretory cells. Details of nectary functioning are based on enhanced structural information, complementary data on nectar discharge after experimental manipulations and the nature of the effluence.Copyright 1998 Annals of Botany Company

Language: English

Document Type: Research article

Affiliations: 1: Institut fur Botanik und Pharmazeutische Biologie, Lehrstuhl fur Pharmazeutische Biologie, Germany 2: Institut fur Zoologie, Lehrstuhl fur Zoologie I, Universitat Erlangen-Nurnberg, Staudtstr. 5, Erlangen, 91058, Germany 3: Dermatologische Klinik der Ruhr-Universitat Bochum, Gudrunstr. 56, Bochum, 44791, Germany

Publication date: 1998-02-01

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