272 Transactitms'. 



The cortex is a wide band of tissue, consisting of large, more or less 

 circular cells, compactly arranged, and with slightly thickened walls. 



5. Gnaphalium Traversii Hook. f. 



The plant is a small perennial herb \-\\ in. high. The plant produces 

 a large number of runners (figs. 31 and- 32), which give rise to new plants 

 at a short distance from the parent plant, so that fairly compact mats are 

 formed by the runners going in all directions. The leaves are ^-H in. long, 



Fig. 31. — Gnaphalium Traversii. Plant (half natural size) to show root-system. 

 Fig. 32. — Gnaphalium Traversii. Plant (half natural size) to show runners. 



spathulate in shape, and clothed on both surfaces, also on the petiole and 

 runner, with a silvery tomentum. The root-system is a mass of tough, 

 fibrous roots. 



Anatomy. 



Leaf (fig. 33). — From the transverse section it is seen that the leaf is 

 very much thickened at the midrib, where there is a large amount of 

 aqueous tissue. The upper epidermis consists of large cells, in which the 

 lateral and inner walls are thin, but the outer are thickened. There is a 

 thin cuticle on both surfaces. The cells of the lower epidermis are much 

 smaller than those of the upper. On both surfaces many of the epidermal 

 cells are produced into long, two-celled hairs, the outer cell being much 

 longer than the basal cell. Stomata are confined to the lower surface, 

 where they are raised above the epidermal cells. The guard-cells are small 

 and have thick walls. Owing to the dense mass of tomentum it is impossible 

 to find the number of stomata per square millimetre. 



The mesophyll consists of palisade and spongy tissue. The palisade 

 tissue consists of a single layer of oval cells in which are numerous elongated 

 chloroplasts. The spongy parenchyma, which is compactly arranged, is 

 composed of rounded or oval cells, also containing chloroplasts. All the 

 mesophyll cells are thin- walled. 



The aqueous tissue in the midrib consists of large, thin-walled, rounded 

 cells, with small air-spaces between them. Above the lower epidermis in 

 the midrib a single layer of these cells contain chloroplasts. 



In addition to the hairs described above, there are club-shaped, glandular 

 hairs, which consist of about 5 cells. 



