MORPHOLOGY OF THE LEAF. 95 



side by side, to the apex of the leaf or to the margin, and are 

 connected by simple transverse veinlets hardly seen. 



Fork-veined, as in the Ferns (and other CRYPTOGAMS where 

 veins are present at all). Here the veins divide and subdivide 

 in a forked manner, and do not reunite. 



285. Of the Keticulate venation the student should carefully 

 note three leading forms : viz., The Feather-veined (pinni-veined) 

 leaf is that in which the venation consists of a midvein giving off 

 at intervals lateral veinlets and branching veimilets, as in the 

 leaf of Beech, Chestnut. In the 'Radiate-veined (palmi-veined) 

 leaf the venation consists of several veins of nearly equal size 

 radiating from the base toward the circumference, each with its 

 own system of veinlets. Ex., Maple, Crowfoot. Lastly, the 

 Tripli-veined seems to be a form intermediate between the two 

 former, where the lowest pair of veinlets are conspicuously 

 stronger than the others, and extend with the midvein toward 

 the summit (see fig. 319). 



286. In parallel-veined venation the veins are either straight, 

 as in the linear leaf of the Grasses ; curved, as in the oval leaf of 

 the Orchis ; or transverse, as in the Canna, Calla, etc. 



iferiew. 271. How does the leaf fiacre in landscape scenery? Its general character? 

 What is the blade ? The petiole? Explain sessile Petiolate. 272. What are stipules* 

 How many? Two special terms. 273. When is the leaf complete? Transformations. 

 274. Describe the petiole of Aspen Of Aster, etc. What peculiar in the leaves of Mul- 

 lein ? What is amplexicaul ? What constitutes a sheath ? What figure ? What are 

 pctiolules? 276. Distinguish simple and compound. 277. Where are the stipules '( Ap- 

 p< arance ? Are they always present ? 278. What of the Kose ? The Pansy ? 279. What 

 oi Oehrese? 280. What of the stipules of Galium ? Of Pond-weed ? Of Grasses ? Of 

 B ittonwood ? What are stipels ? 282. Structure of the Blade. What is Venation ? Its 

 oigans? Why veins rather than ribs f 283. Define Midvein. What leaf has such ? De- 

 fine vein, as in Maple. Veinlets. Veinulcts. 284. Name and describe the Venation of 

 the Exogens Of the Endogens Of the Ferns. 285. What leaf is pinni-veined? 

 Palmi-veined ? Tripli-veined ? Parallel venation how varied 1 



CHAPTER XXI. 



MORPHOLOGY OF THE LEAF CONTINUED. 



,JS7. That infinite variety of beautiful and graceful forms for 

 which the leaf is distinguished, becomes intelligible to the stu- 

 dent only when viewed in connection with its venaticn. Since 

 it is through the veins alone that nutriment is conveyed for the 



