15 



PLATE VIII. 



HISTOLOGY OF FLOWEKING PLANT. 



STBM 



DIAG. 1. TRANSVERSE SECTION of a one-year-old stem of Horse Chestnut 

 Pith or medulla in centre. 

 Fibro-vascular bundles arranged in a ring round the pith 



Wood or xylein, including medullary sheath. 



Cambium, a soft cellular layer. 



Last or phloem outside the cambium. 

 Cortex, connected with the pith by the medullary ray& 

 Epidermis. 



Note. The part of the stem outside the soft cambium is readily removable, and is the separable bailc. 



Fio. 1. TRANSVERSE SECTION of same stem under the microscope 

 Pith, consisting of parenchyma cells. 

 Fibro-vascular bundle 

 Wood or xylein 



Vessels, large openings. 

 Wood-cells between the vessels. 

 Cambium, small thin-walled cells. 

 Bust or phloem 



Soft portion, made up of thin-walled cells. 



Hard portion, or liber layer, made up of round thick-walled cells, the central cavity 



being almost obliterated. 



Medullary rays, brick-shaped cells between the fibre-vascular bundles. 

 Cortex, angular cells, parenchyma. 

 Epidermis, a single layer of squarish cells. 

 FIG. 2. LONG. SECTION of the Horse Chestnut stem 

 Pith-cells. 



Fibro vascular bundle 

 Wood- 

 Spiral vessels of medullary sheath, elongated tubes with spirally thickened walls. 

 Annular vessels, elongated tubes with ringlike thickenings. 

 Dotted ducts, elongated tubes thickened so as to leave thin places, the dots. 

 Wood-cells, elongated, and when older with thick walls, and then called woody 



fibres or wood prosenchyina. 

 Cambium, thin-walled cells. 

 Bast- 

 Soft bast, elongated thin-walled cells. 



Hard bast, thick-walled and elongated cells forming the flexible bast fibrea 

 Cortex, parenchymatous cells. 

 Epidermis, a single layer of cells. 



FIGS. 3, 4. SECTIONS of stem of Butcher s Broom magnified 

 Differences from Horse Chestnut stem 



Fibro-vascular bundles are not arranged in a ring round pith, but scattered irregu 

 larly. 

 No cambium and therefore no provision for increase after first year. 



