Foweraker. — Mat-plants and Cushion-plants of Cass- Biver Bed. 11 



small. Chlorenchyma peculiar : on upper surface a single layer of 

 cylindrical cells and on lower surface a single layer of spheroid cells 

 densely packed with chlorophyll grains. No spongy parenchyma of usual 

 type, "but between the chlorenchyma layers is a layer of large clear thin- 

 walled polygonal cells with few chloroplasts, evidently a water-storage 

 tissue. Lower epidermis easily separates from mesophyll, but it is difficult 

 to remove upper epidermis. Vascular bundles have a large-celled sheath. 



In a typical adult leaf the structure is but slightly different from that 

 of the young form. The cuticle is slightly thicker. The chlorenchyma may 

 be of two layers of cells on both surfaces of leaf. Aqueous tissue and 

 vascular bundles, &c, are similar to those of young leaf. 



a 



water storage tissue 



E. F. del. 



Fig. 3. — Raoulia tenuicaulis. Young leaf, (a) Diagram of transverse section : 

 shaded portion is chlorenchyma ; (6) transverse section of lamina. 



(c.) Root. — The roots are given off from the lower surface of the creeping- 

 stems. They are very fine and hair-like, copiously branched, and of a 

 blackish-brown colour. A large quantity of roots is given off from all over 

 the lower surface of the stems. The creeping marginal stems, not far behind 

 their slightly upturned tips, soon commence to give off copious roots. In 

 plants where filling-matter is in considerable quantity, roots are also given 

 off into this by the erect branches. 



Regarding their anatomical structure, sections of older roots show struc- 

 ture not much unlike stem. There is a central column of lignified elements 

 surrounded by phloem. External to this comes the endodermis, and finally 

 the cortex, which becomes either lignified or suberized, and is gradually 

 thrown off from the exterior. 



(d.) Flower and Fruit.- — The flower-heads, of the usual Composite type, 

 are borne at the ends of the branchlets. In an adult mat about half the 



