.17 



PHARMACEUTICAL BOTANY 



Third Type. Instead of two parallel subsidiary cells, four are cue 

 off, as in Heliconia, in species of Tradescantia, Araucaria, or four co 

 five, as in Ficus elastica, or four to five or more, as in the Coniferce 

 and Cycads. 



Fourth Type. Instead of only four subsidiary cells, each of these 

 again subdivides by parallel walls, more rarely by radial walls, into 

 eight radiating subsidiary cells, as in Maranta bicolor, Pothos argyraa, 

 some of Proteacece, etc. 



Fifth Type. The "stomal mother-cell" divides once or several 

 times before becoming the true mother-cell of the stoma. As a 

 result of the divisions there are also formed one or more subsidiary 

 cells. This mode of development is seen in the Labiates, Papilio- 

 nacece, Cruciferce, Solanacece, Crassulacecz, Cactacece, and Begoniacece, 

 also in a number of ferns. 



Histologic Differences between Leaves of Dicotyledons and 

 Monocotyledons. The following may be cited as broad compara- 

 tive histologic differences between Dicotyl and Monocotyl leaves: 



Monocotyl Leaves 

 . Epidermal cells usually elongate 



and equilateral. 

 . Stomata larger. 



Dicotyl Leaves 



Epidermal cells usually iso-dia- 

 metric or sinuous. 



The stomata are on the whole more 

 numerous but smaller. 



Non-glandular and glandular hairs 

 frequent, or upper but more fre- 

 quent on lower surface, or both. 



Leaf glands which excrete varied 

 products are rather abundant. 



Water stomata over the upper sur- 

 face, more rarely over the lower 

 surface, are frequent, especially 

 along margins of leaves. 



Palisade and spongy parenchyma 



. in dicotyledons are more distinct 

 and palisade parenchyma is 

 denser. 



The vascular bundles, in their in- 

 trinsic elements, are more indur- 

 ated but the accessory fibrous 

 sheath is feebly developed. 



A greater variety of accessory prod- 

 ucts of assimilation are de- 

 veloped. 



3. Hairs rare in MonocotyJs. 



4. Leaf glands rare and only seen as a 



rule on the sepals. 



5. Water stomata absent or very rare. 



Present in some Araccce. 



6. Palisade and spongy parenchyma 

 are less distinct and dense. 



The vascular bundles, in their in- 

 trinsic elements, are less indur- 

 ated. The fibrous sheath is 

 strongly developed. 



A comparatively small variety of 

 accessory products of assimila- 



tion are developed. 



