240 Transactions. 



Anatomy. 



Leaf. — Both the upper and lower epidermis consist of large cells, some- 

 what rectangular in transverse section ; the walls are slightly thickened, 

 the external ones more so. A thin cuticle is found on both surfaces. 

 Stomates are confined to the lower surface. The guard-cells are large and 

 thick-walled, and are at the same level as the other epidermal cells. 



The chlorenchyma is differentiated. The palisade tissue consists of about 

 3 layers of large irregular cells, which are somewhat loosely arranged, so 

 that there are moderately large air-spaces between the cells. The spongy 

 tissue consists of very irregular cells, which are loosely arranged. Both 

 palisade and spongy tissues contain numerous fairly large chloroplasts. 



The vascular bundles are small, and each is surrounded by a sheath of 

 small thin-walled parenchymatous cells which contain a very few chloro- 

 plasts. Associated with both ploem and xylem is small-celled parenchyma. 

 The amount of lignified tissue is small. 



Stem. — The epidermis is composed of somewhat squarish cells with 

 thickened cell-walls. A moderately thick cuticle is present. Some of the 

 epidermal cells contain a few chloroplasts. Stomates are frequent, the 

 guard-cells, which have thickened walls, being at the same level as the other 

 epidermal cells. 



The cortex consists of roundish or irregular cells. This tissue can be 

 divided into two regions — an outer one containing numerous chloroplasts, 

 and an inner colourless region. The cells of the chlorenchyma are rounded 

 or irregular, and their walls are slightly thickened. The colourless cortex 

 consists of somewhat squarish cells regularly arranged. 



There are 6 vascular bundles, with a mass of pericycle fibres above the 

 phloem. 



The pith is solid, and consists of thin-walled parenchymatous cells. 

 The medullary rays are wide, and are composed of large round or polygonal 

 cells with thickened lignified walls. 



8. Notothlaspi australe Hook. f. 



Growth-form. — A small densely tufted alpine herb, 2-1 in. in height. 

 It is " usually much branched from the base ; branches leafy, spreading, 

 1-4 in. long. Leaves radical and cauline, numerous, \-\\ in. long, petiolate, 

 linear- or oblong-spathulate, entire or crenate, glabrous or with a few 

 cellular hairs." 



Anatomy. 



L"af (figs. 11-12). — The cells of both the upper and the lower epidermis 

 are large, and oval in transverse section, and have their external walls 

 thickened. There is a thin cuticle on both surfaces. Stomates are very 

 numerous on both surfaces ; on the upper surface of the leaf they are 

 6 1 ghtly sunken, but not on the lower. The guard-cells are small and have 

 their walls thickened. On the younger leaves there are some hairs ; on 

 the older leaves there are a few on the lower part of the blade. The hairs 

 are large, thin-walled, and slightly cutinized at their base. They contain 

 protoplasm, and are probably water-absorbing hairs. They are shown in 



The chlorenchyma is differentiated. The palisade tissue consists of 4 

 'ayers of cells, the layer adjacent to the epidermis being composed of 

 roundish cells and the other 3 layers of large elongated cells. Chloroplasts 

 are numerous but small. There are small intercellular air-spaces between 

 the cells. The cell-walls are thin. 



