ox THE ANATOMY OF MAGNOLIACE^. 



IP.O 



tlie peliole is variable, in some species exceeding twenty, in others 

 l)eing miK'li fewer. These l)und]es are g-eiierally isolated from one 

 another in the basal portion of the petiole, but in its u])per portion they 

 become gradually united so as to form a ring enclosing the ])ith. 

 This arrangement is usually very regular, but sometimes several liundlcs 

 stand isolated outside the main ring, and disturl) the regularity of the 

 ai-rangement. The sclerenchymatous fibres are very well deve!o])ed 

 and constitute the bundle sheath. They are generally unlignified 

 at the b:isal portion of the petiole, but in Liriodendron some of these 

 fibres are lignified eNen in the basal portion. The diaphragms .are 

 present in the species examinech In several cases, however, tiiey are 

 only faintly represented by a few sclerol)lasts found in the pith; while 

 in others (c. <)., Miclirlia fuscata), a bro.ad mass of sclerenchymatous 

 cells constitutes the diaphragm. 



Blade. — With the exception of IJriodciidron the cuticle is general- 

 ly well-developed. In MidieUn and Maipiolia epidermal hairs are 

 generally met with, especially on the lower surface of the leaf; wliilc 

 in Liriodendron many epidernud cells of the lower side of the leaf are 

 provided eacli with a little ])rotuberance, which is really an im])erfect 

 hair. In many cases the hair is not an elongation from a single 

 epidermal cell, but several cells take part in ibrming its l):isal portion, 

 as will be seen in referring to the figures, 25 and '2(1 (PI, V). The 

 stomata are generally elliptical in form, but in MofiHolio (jntnditlorit 

 they are rather I'oundish, the curvature of the guard-cells being very 

 great. In Magnolia jnimila the cuticle is much I'aised at the entrance 

 of the stomata, and presents a cu])-like appearance, reminding us of 

 the stomata of TrocJiodemlrox (PI. V, Fig. oO). lu MaijiioJia (jrandifJora 

 there is found between the epidermis and the palisade-parencliyma a 

 single layer of parenchymatous cells, which do not contain chlorophyll 

 grains (PI. \\ Fig. :^9). This layer extends to tlie verv margin of 



