You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
5.45<br />
5.44 IS of the petiole of the dicotyledon Phaseollls<br />
vulgaris (bean). A large crcsccm-shaped vein and;] pair of<br />
sm:!.lliateral veins arc present. The extensi"e xylem (1) of<br />
rhe large vein lies adaxially whilst the phloem (2) is<br />
delimited by stl"3nds of fibres (3). An extensive hypoderm:!.l<br />
band of sclerenchyma (4) is evident and Ihe remaining<br />
ground tissue is parenchymalous. (G-Os, LM x 85.)<br />
1 X"km<br />
2 Phloem<br />
3 Fibre strands<br />
4 ScleTeflChyma<br />
5.45,5,46 POffcd spccimen of the Ji,otylcdoll Oxalis Qllgil/aris showing sleep movements. In the dny-time (SA;) the<br />
three leaflets of each leaf are extended bur thcy droop at nigh! (5.46). This movemenr is caused by loss of rurgor in<br />
sp«:ialised tr,ICfS of parenchyma [issue loc:lfed in a ioint·like thickening (pulvinus) siTuated at [he top of the peTiole just<br />
benearh the leaflets.<br />
114
Change language