THE LEAVES. 



31 



be carefully observed: thus the Melilot (fig. 117) has apirmately tri-foliolate leaf, 

 but the Trefoil (fig. 118) a digitately ternate 1 leaf, all the leaflets springing from 

 the top of the petiole. 



The leaf is bipinnate (f. bipinnatum), when the secondary petioles, instead of each 

 ending in a leaflet, form so many pinnate leaves (Gleditsckia triacanthos, fig. 119) ; 

 tripinnate (f. tripinnatum) , when the secondary petioles bear as many bipinnate 

 leaves (Actcea spicata, fig. 120) ; tri-ternate, when the common petiole bears three 

 secondary petioles, which each bear three tertiary petioles, each of which again bears 

 as many digitately tri-foliolate leaves (Actwa racemosa, fig. 121). A pinnate leaf 

 with all its leaflets in lateral pairs is termed pari-pinnate (f. pari-pinnatum) ; when 

 in addition it is terminated by a solitary leaflet, the leaf is impari-pinnate 

 (f. impari-pinnatum., Kobinia, fig. 114). 



122. Cancalis. Decompound leaf. 



12:f. Potato. 

 Interruptedly pinnate leaf. 



124. Agrimony. 

 Pinnatiseet leaf. 



12"). Orobns. 

 Pinnate leaf with unequal leaflet 

 changed into a very short filament. 



A leaf is laciniate or decompound (f. laciniatum, decompositum) , when, without 

 being really compound, it is cut into an indefinite number of unequal laciniae 

 (Caucalis Anthriscus, fig. 122; Water Crowfoot, fig. 71), as in most umbelliferous 

 plants (Parsley, Chervil, Hemlock, Carrot, Angelica, &c.). 



A leaf is interruptedly-pinnate or -pinnatisect (f. interrupti-pinnatum, -pinnati- 

 sectum], when the leaflets or divisions are alternately large and small (Potato, fig, 

 123; Agrimony, fig. 124). 



Tendrils. Tendrils (cirri) are thread-like, more or less irregularly spiral organs, 

 which usually coil round neighbouring bodies, and thus support the plant. The leaf 

 is cirrhose (f. cirrosum), when one or more of its leaflets is reduced to its median 

 nerve, and becomes a tendril. In the Bitter Vetch (fig. 125), the tendril is simple 

 and very short, because it is only the terminal leaflet which is thus transformed. 

 In the Pea (fig. 126), and in Vetches (fig. 127), the three terminal leaflets are changed 

 into tendrils. In another Vetch (Lathy rus Aphaca, fig. 128) all the leaflets are 

 suppressed, and the whole leaf is reduced to a filament without parenchyma (v); in 



1 More correctly a digitate]}- tri-foliate leaf. Er>. 



