Divergent pollination systems in the cleistogamous species,Collomia grandiflora (Polemoniaceae)
Journal Protoplasma
Publisher Springer Wien
ISSN 0033-183X (Print) 1615-6102 (Online)
Issue Volume 159, Number 1 / February, 1990
DOI 10.1007/BF01326632
Pages 26-34
Subject Collection Biomedical and Life Sciences
SpringerLink Date Thursday, March 31, 2005
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Divergent pollination systems in the cleistogamous species,Collomia grandiflora (Polemoniaceae)
L. C. Sanders1, K. J. Eckard1 and E. M. Lord1 Contact Information
(1) Department of Botany and Plant Sciences, University of California, 92521 Riverside, CA, USA
Received: 30 March 1990 Accepted: 19 July 1990
Summary A structural study of pollination in the dimorphic flowers ofCollomia grandiflora, a cleistogamous species, reveals significant differences in stigma behavior during pollination, stylar structure, the timing of generative cell division, and pollen tube growth rate patterns. The cleistogamous flower shows a loss of protandry and the stigma is receptive only after reflexing and closing of its lobes. In contrast, the chasmogamous stigma is receptive when reflexed and closes when pollen has been deposited on the lobes. Pollen tube penetration of the dry stigma papillae and entry into the style is similar in the two morphs. The chasmogamous style is solid and the cleistogamous style partly hollow. The matrix of secretion produced by the transmitting tract cells is mainly carbohydrate with a trace of lipids. It is fibrillar in nature and appears to be partly comprised of wall material from the transmitting tract cells. In the chasmogamous pollen, the generative cell enters the tube before division, which occurs between 30 and 60 min after pollination. This division correlates with an increased growth rate for the pollen tube. In the cleistogamous pollen, contact with the stigma triggers generative cell division inside the hydrated pollen grain before germination. The two resulting sperm cells exit the grain 15–30 min after pollination when the pollen tube is in the stigma lobes. The cleistogamous pollen tube shows only one phase of growth which occurs at a rate similar to that of the slow, first phase of the chasmogamous pollen.
Keywords Cleistogamy - Generative cell division - Pollination - Collomia grandiflora
Abbreviations CH chasmogamous - CL cleistogamous - DAPI 4prime, 6-diamidino-2-phenylindole
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