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Spatial relation between xylem and phloem in the stem ofHibiscus cannabinusL. (Malvaceae)

 

作者: KATHERINE ESAU,   IELENE B. MORROW,  

 

期刊: Botanical Journal of the Linnean Society  (WILEY Available online 1974)
卷期: Volume 68, issue 1  

页码: 43-50

 

ISSN:0024-4074

 

年代: 1974

 

DOI:10.1111/j.1095-8339.1974.tb01746.x

 

出版商: Blackwell Publishing Ltd

 

数据来源: WILEY

 

摘要:

The distribution of the phloem in relation to the xylem was examined in the stem ofHibiscus cannabinusL. with reference to a report in the literature that this species has internal (intraxylary) phloem, a feature not previously observed in the Malvaceae. In the present study, the stem was found to have phloem only outside the xylem (external or extraxylary phloem). In the protophloem, the sieve tubes are obliterated while the internode elongates and the associated cells become fibres with thick secondary walls. Fibres occur in the secondary phloem also. As seen in transections of stems, the secondary xylem forms a continuous ring. The primary xylem extends in the form of arcs into the pith. The tracheary cells of the protoxylem become crushed or completely obliterated in elongating internodes. The associated parenchyma cells either retain thin walls or develop secondary thickenings.

 

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