Betts. — Auf ecology of Plants of Peridot ite Belt, Kelson. 141 



13. Pimelea Suteri T. Kirk. 



Growth-form. — " A small much-branched shrub, 4-12 in. high ; branches 

 spreading or suberect, often tortuous ; the younger ones sparingly pilose 

 with rather long straight silky hairs ; bark, dark red-brown or black. Leaves 

 crowded, shortly petiolate or nearly sessile, erecto-patent, about \ in. long, 

 narrow linear-lanceolate, subacute, coriaceous, concave above, both surfaces 

 glabrous or rarely with a few lax hairs, margins and apices ciliated with 

 long straight hairs." 



Anatomy. 



Leaf (figs. 4, .5). — Fig. 4 gives a diagrammatic view of the transverse 

 section, while fig. 5 shows a portion of the section in detail. 



Both the upper and the lower eiaidermis consist of narrow rectangular 

 cells, which have their lateral and internal walls slightly thickened and the 



external ones considerably 

 thickened. There is a cuticle 

 on both surfaces. Stomates 

 are found on both surfaces, 

 and are slightly sunken below 

 the thickened epidermal 

 walls. The guard-cells have 

 thickened walls, and the 

 opening is protected by guard- 

 cell ridges. 



Below the epidermis, on 

 both surfaces, there is a 

 hypoderma of very large 

 colourless cells : these form 

 mucilage-sacs. 



The chlorenchyma is dif- 

 ferentiated. The palisade 

 tissue is found on both sides 

 of the leaf. It consists of 

 2-3 rows of cells, these 

 being somewhat larger in the 

 upper than in the lower pali- 

 sade tissue. The walls are 

 thin and contain numerous 

 chloroplasts. Some of the 

 cells contain tannin. The 

 air-spaces in this tissue are 

 small. Beneath the stomates 

 the layer of mucilage-cells is - 

 interrupted by the palisade 

 tissue. Beneatli each stoma 

 there is a fairly large cavity. 

 The spongy tissue consists 

 of somewhat irregular cells 

 with numerous chloroplasts. The air-spaces are small. Most of the 

 cells contain tannin. 



Surrounding the vascular bundle there is a sheath of thin-walled paren- 

 chymatous cells which contain tannin. The xylem is formed of wood-fibres 

 and tracheides of small diameter and with thickened walls. The xylem is 



Fig. 4. — Pimelea Snterl. Transverse section of 

 leaf (diagrammatic) ( X 36). a, epidermis ; 



b, mucilage-cells ; c, chlorenchyma. 



Fig. 5. — Pimelea Suteri. Transverse section of 

 leaf (X 17.5). a, cuticle; b, epidermis; 



c, mucilage-sac ; d, palisade parenchyma ; 

 c, bundle-sheath ; /, xylem ; g, phloem ; 

 h, sclerenchyma ; *, stoma. 



