The Science of Plant Growing 



vening partitions, becoming continuous and forming what is known as 

 laticiferous tissue (fig. 8). 



Spiral and Celandine Laticiferous 

 Annular Vessels Tissue 



Dandelion Laticiferous 

 Tissue 



Plant Tissues. All the above forms of cells and many more unite 

 in certain definite relations to one another, forming a tissue (fig. 9). Most 

 flowering plants, Ferns, Lycopods, and 

 Selaginellas have representatives of 

 various forms of cells, wood fibres, and 

 vessels in their tissues, and are spoken 

 of as fibro-vascular plants, and consti- 

 tute the most highly developed members 

 of the vegetable kingdom. A mushroom 

 is not a fibro-vascular plant, as it is 

 made up entirely of branching threads 

 of thin-walled cells. 



Uses of Different Cells. The 

 thickened outer cells of leaves and 

 young stems are of a protective nature, 

 so far as the cuticle is concerned, while 

 the interior is thickened to impart 

 strength. Wood fibres give rigidity to 

 the stems of herbaceous plants and in 

 a greater degree to trees, which have 

 the greatest number of them; and they, 

 in conjunction with the continuous tubes 

 or vessels, serve for the rapid convey- 

 ance of liquids, containing ingredients 

 of plant food, as well as elaborated food 

 being carried to the points of growth or to be stored. The laticiferous 



Fig. 9. Cut illustrating various tissues. To 

 the left Spiral Vessels, followed by long Conduct- 

 ing Cells. These are succeeded by Cellular Tissue 

 or Parenchyma. In some of the square cells are 

 Crystals of Oxalate of Lime. In the longer cells 

 are groups of Needle-like Crystals called Raphides. 

 To the extreme right are Pitted Cells. 



