90 



FOEMS 01" SIMPLE LEAVES. 



downwards and are acute (fig. 180), the leaf is sagittate (sagitta, an 

 arrow) ; when they proceed at right angles, as in Rumex Acetosella, 

 the leaf is hastate (hasta, a halbert) or halbert-shaped. When a simple 

 leaf is divided at the base into two leaf-like appendages (fig. 184), it 

 is called auriculate (auricula, little ear). When the veins spread out in 

 various planes, and there is a large development of cellular tissue, so as 



to produce a succulent leaf, such forms occur as conical, p-ismatical, 

 ensiform or sword-like {ensis, a sword), acinaciform {acinaees, a 

 scimitar) or scimitar-shaped (fig. 187), and dolabriform (dolabra, an 

 axe) or axe-shaped (fig. 186). When the development of cells is such 

 that they more than fill up the spaces between the veins, the margins 

 become wavy, crisp, or undulated, as in Humex crispus and Rheum 

 undulatum (fig. 189). By cultivation the cellular tissue is often 



much increased, giving rise to the curled leaves of Greens, Savoys, 

 Cresses, Lettuce, etc. In rushes the shoots which act as leaves are 



Fig. 179. Ronnded entire leaf, ending in a short point. Kg. 180. Sagittate or arrow- 

 sliaped leaf of Sagittaria. Fig. 181. Lanceolate, acute leaf, with minute teeth or dentations 

 at the margin. Fig. 182. Subulate or awl-shaped leaf. Fig. 183. Whorl or verticil of 

 linear-obovate leaves. Fig. 184. Auriculate lanceolate leaf, oblique at the base, with 

 minute toothings at the margin. Fig. 185. Pedate or Pcdatifid leaf of Hellebore. Eadi- 

 atlng venation. Fig. 186. Dolabriform or axe-shaped fleshy succulent leaf. Hidden- 

 veined. Fig. 187. Acinaciform or scimitar-shaped succulent leaf. Hidden-veined. 

 Fig. 188. Oval leaf with converging veins ; not reticulated. Fig. 189. Palmately-lobed 

 leaf, crisp or undulated at the margin. Radiating venation. 



