Secretion-7

Lecture Directory	Prior Page	Home Pag	Next Page
Secretion-7
Leaves of Olona (Touchardia )		Laticifers in the stem of Olona were used to produce an extremely fine and unusually strong twine. It is extremely resistant to salt water and was the best naval cordage until the invention of synthetic fibers like nylon. The ancient Hawaiians used it to make their most prized adornments like feathered capes and helmets. Olona twine was used in to make fish nets and many other items that were used in the ocean.
Laticifers in the stem of Olona - The Laticifers are in the Ground Tissue which lies between the Phloem and the Epidermis. Their walls are birefringent in polarized light (Left Image) . The image on the right is a negative image & the Laticifer walls are dark.
		Olona Laticifers - Long Section Viewed with Polarized Light The birefringence is due to the thickness of the cell walls. The cells are very long. This is typical for Laticifers but the degree of wall thickening is atypical. The thickness of the cell walls and their length contribute to possibility that these play a role in structuraal support as well as secretion.
		Olona Laticifers Stained with Toluidine Blue - Note that the thick Laticifer cell walls have stained heavily for Pectins. This means that their walls are probably unlignified. Unlignified walls are less rigid. Olona seems to grow on slopes which are unstable. They are somewhat vine-like. Perhaps the absence of lignin may allow the stems to be more flexible and streachable. These qualities might be important for survival in unstable habitats.
		Olona Laticifers Unstained - Note the yellow-orange Latex present in one of the Laticifers. The nature of the latex is completely unknown. Note the thickness of the cell walls and the pits in the Laticifer at the lower left.
		High Magnification view of a Laticifer from Olona - It is very unusual for Laticifers to have thick walls. It would be interesting to look at other closely related plants to see if their "Fibers" are actually Laticifers.