Herriott. — Plants from the Southern Islands. 385 



form of the adult leaf, but its anatomical structure is probably 

 very similar. Young as it was, it presented some striking points 

 of difference from the older leaves of the other two species, espe- 

 cially as regards its succulent habit. 



Anatomy (figs, la, lb). — There is a very thick but smooth 

 cuticle (cut.) on the upper surface which gives the leaf its shiny 

 appearance. Below this comes the upper epidermis (ep.), with 

 its large and thick-walled cells interrupted at frequent intervals 

 by stomata (st.). The walls are collenchymatous, staining blue 

 on the application of chlor-zinc-iodine. The cells of the lower 

 epidermis (l.ep.) are somewhat smaller and not so thick- walled. 

 No hairs are present. The chlorenchyma (chlor.) is differentiated 

 into palisade (pal.) and spongy (sp.), the spongy parenchyma occu- 

 pying the greater area. The palisade tissue consists of the or- 

 dinary palisade cells in 3-4 layers, densely filled with chlorophyll 

 corpuscles, giving the leaf its characteristic dark-green colour. 

 In this young leaf the palisade tissue was continued in two layers 

 above the small vascular bundles (v.b.) which occurred scattered 

 through the spongy tissue. In the other two species the vascular 

 bundles interrupt the green chlorenchyma with a mass of colour- 

 less cells. The spongy tissue (sp.) is very loosely arranged, leav- 

 ing large air-spaces between the cells. In the central portion 

 of the leaf the cells are large and sparingly filled with chloro- 

 phyll ; some occur as colourless thin-walled parenchyma cells 

 (par.). Adjoining the lower epidermis, however, the cells are 

 much smaller and round, and also more abundantly filled with 

 chlorophyll. The vascular bundles (v.b.) are each surrounded 

 by a more or less sharply defined endodermis (endo.), and this is 

 again surrounded with a layer of larger thin-walled and colour- 

 less parenchyma (p.s.) cells. Each bundle consists of xylem 

 (xy.) on the upper surface and phloem (ph.) on the lower. 



Here the effects of the moist or semi-aquatic habitat are seen 

 in the development of larger air-spaces. 



Ranunculus subscaposus, Hook, f., Fl. Antarc, i, 5. 



" Radical leaves on slender petioles, 3 in. to 8 in. long, blade 

 broadly triangular-ovate, slightly cordate, 3-foliate or 3-partite 

 to base ; leaflets cuneate at the base and more or less deeply 

 incised or toothed, or rarely entire with margins deeply cut ; 

 cauline similar."* 



" Both petiole and lamina on both surfaces are densely 

 clothed with appressed whitish hairs. "f 



, . *■*■ ■ 



* Kirk (1899), p. 15. 

 f Cockayne (1903), p. 273. 



13— Trans. 



