22 



i^LKMENTS OF BOTANY. 



Bosidos fiimplo and conipouiid leaves, there arc other abnormal forniH, 

 Huch HH tendrils, spines, and pitchers, to which wo cun barely alliuh. 

 Tendrils (Fi<^'. '>V2) and Hpiiiea arc but reduced IcavcH, while pitchcrH an 

 leaves which have underjj[()ne ehan<^eH of structure; to tit them for Hpecial 

 purposes, ua for exuniijle, the eutrappiug of inisects. 





Fio. 81.— A bi-plnnate'.y compound leaf. 



Fio. 82.— Compound leaf of pea, with the tcmiinnl 

 leaflotH chantifud to toiulrlls. The expanded leafletfi at the 

 bux(! nro foliaccouH stipu.^tH. 



As remarked above, a leaf may or may not have a distinct petiole. In 

 the latter (!ase the base of the blade is attached directly to the stem, with 

 or without an articulation. In all deciduous plants — that is, those whose 

 leaves fall away at the end of the growing season — the articulation is pres- 

 ent whether there be a petiole or not. In endogono is plants the articu- 

 lation is absent, the leaves, at the end of the growin-^ season, dying away 

 gradually. 



Li some cases where the jjetiole is absent, the base of the leaf encircles 

 or clasps the stem. Occasionally the leaf appears as though perforated by 



