OR, PLAIN TEACHING. 



299 



803 



805 



806 



807 



808 



809 



810 



811 



812 



813 



Some leaves are silver- 

 edged, 803, as in the case 

 of certain geraniums, 

 giving the shrub a very 

 pretty effect: others are 

 dark-edged, or have a 

 dark inner border. 



While, in a few ex- 

 amples, there is a light 

 and leaf- like mark ex- 

 tending along the midrib, 

 804. 



Occasionally the colour 

 is arranged in zones, a 

 feature which is observ- 

 able in the aloe and cactus 

 tribes, 805. 



Some leaves are deeply 

 indented at their base, and 

 reflected upon the petiole, 

 806. 



Others are tendriled at 

 the apex, 807. 



Some are deeply em- 

 bedded in the stem, and 

 are termed stem-clasping, 



Others are linear, and 

 grow in pairs, or in bun- 

 dles, united at the base 

 by a sheath, 809. 



Some are arranged in a 

 series of points or rays, 

 diverging from a centre, 

 810. 



Others form large /un- 

 like fronds, 811. 



Some are thickly set 

 with sharp spines, the 

 flowers being sessile upon 

 the leaves or stalks, 812. 



Others are arranged as 

 a series of scales, the 

 flowers forming a head at 

 tie top of a compact 

 column, 813. 



815 



816 



817 



818 



820 



821 



822 



823 



There are sometimes 

 varieties of leaves on the 

 same plant, as in the glin- 

 dista, one of the acacias, 

 814. The same may be 

 observed upon the jessa- 

 mine. 



Leaves which are united 

 to the stems without pe- 

 tioles, have been already 

 described as sessile; but 

 when they run down the 

 stem, as in some of the 

 thistles, they are decurrent, 

 815. 



The scales which cover 

 leaf-buds are called teyu- 

 menta, their office being to 

 protect the delicate unde- 

 veloped organs. In many 

 plants, the scales are ulti- 

 mately developed into 

 leaves, 816. 



In some instances leaves 

 are formed in unusual 

 situations, as upon the 

 stems, leaves, and bulbs 

 of plants. These leaves 

 being unusual, are called 

 adventitious, 817. 



The sharp, pointed pro- 

 cesses on certain stems 

 are prickles, 8 1 8 . In some 

 plants they are the growth 

 of a single year, as in 

 the rose and bramble; in 

 others, of two or three 

 years. They differ frrin 

 spines, as those of the sl« e, 

 819, which are prolonga- 

 tions of the wood of the 

 tree, and cannot, like the 

 prickles, be detached from 

 the cuticle by the pressure 

 of the thumb, nor do they 

 fall off. 



Hairs are minute 

 thread-like processes, 

 generally more or less 

 transparent, 820. They 

 are rough, silky, and 

 cobweb-like. When fine, 

 and arranged on a border, 

 they are called cilia. 



Stems which are three- 

 sided are angular f 821. 



Those which are marked 

 by rings, or circles, are 

 annulated, 822. 



The articulations or 

 joints of stems are nodi. 

 They are well defined in 

 the stems of wheat, oats, 

 and other grasses; an I 

 more particularly i:i 

 bamboos and canes, 8*23. 



