LlCSdON O.J 



rKIlKOI.IATK I.KAVKS, KTC 



67 



are hipinnatc, i. o. twice piniiafr, a^ in Fi;_'. l')0. If tliPso Ic^aflota 

 ■vvt-n; again (li\ idfd in llio same way, tin; leaf would hvvxmm l/irice 

 pinnate, or tripinnalc, as in many Acac'ias. Tiie first divisions are 

 vnWcd pi lUKr ; the oxhor^^, pinnules ; and the last, or little Mados, 

 ivdjiets. 



172. So till! palmate leaf, if again compounded in the same w.ay, 

 becomes twice pnlmatc, or, as we say when the divisions are in 

 threes, /M'/Ve tcrnate (in Latin form hitcrnate) ; if a third time com- 

 pounded, thrice tcrnate or tritcrnatc. liut if the division goes still 

 furtluT, or if the degree is variable, Ave simply say that the leaf is 

 decowpound ; either palmately or pinnat«'ly so, as tlie case may be^ 

 Thus, Fig. 108 represents a lour times ternately coin[X)ini<l, in other 

 •words a ternatclif decompound, leaf of our common jNIeadow Rue. 



170. So exceedingly various arc the kinds and shapes of leaves, 

 that we have not yet exhausted the sui)ject. "We have, however, 

 mentioned the j)rincipal terms used in descrii)ing them. ]\Iany 

 others will be found in the glossary at the end of the volume. Some 

 peculiar sorts of leaves remain to be noticed, which the student might 

 not well understand without some explanation ; such as 



171. Pcrfolialc Leaves. A common jind simple case of this sort is 

 foinid in two species of Uvuhu'ia or Bellwort, where the stem appears 

 to nni through the bhule of the leaf, 

 near one end. If we look at this plant 

 in summer, after all the leaves are 

 formed, we may see the meaning of this 

 at a glance. For then we ofivn find 

 upon the same stem such a series of 

 leaves as is given in Fig. 131 : the low- 

 er leaves are perfoliate, those; next aI)ove 

 less so ; then some (the fourth and fifth) 

 with merely a heart-shaped clasping 

 base, and finally one that is merely 

 sessile. The leaf, we perceive, becomes (^Z^ 

 perlbliate by the union of the edges of 

 the base with each other around the 

 stem ; just as the shield-shaped leaf. Fig. 

 102, comes from the union of the edges of the base of such a leaf 

 ;is Fig. 101. Of the same sort are tlw; up|)<'r leaves of most of 



nc. ini. leaves nf fvulnria (nrllwort) ; llio lower oneii perfoliato, (Im oUi«r« merely 

 ela.s|iiiig, or tlio ii)i|>eriU(>Nl only dushIIo. 



