176 
PHARMACEUTICAL BOTANY 
Third Type. —Instead of two parallel subsidiary cells, four are cut 
off, as in Heliconia , in species of Tradescantia, Araucaria , or four to 
five, as in Ficus elastica , or four to five or more, as in the Conifer a 
and Cycdds. 
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 argyrcea, 
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 Labiatce, Papilio- 
nacece, Cruciferce , Solanacece, Crassulacece, 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: 
Dicotyl Leaves 
1. Epidermal cells usually iso-dia- 
metric or sinuous. 
2. The stomata are on the whole more 
numerous but smaller. 
3. Non-glandular and glandular hairs 
frequent, or upper but more fre¬ 
quent on lower surface, or both. 
4. Leaf glands which excrete varied 
products are rather abundant. 
5. Water stomata over the upper sur¬ 
face, more rarely over the lower 
surface, are frequent, especially 
along margins of leaves. 
6. Palisade and spongy parenchyma 
in dicotyledons are more distinct 
and palisade parenchyma is 
denser. 
7. The vascular bundles, in their in¬ 
trinsic elements, are more indur¬ 
ated but the accessory fibrous 
sheath is feebly developed. 
8. A greater variety of accessory prod¬ 
ucts of assimilation are de¬ 
veloped. 
Monocotyl Leaves 
1. Epidermal cells usually elongate 
and equilateral. 
2. Stomata larger. 
3. Hairs rare in Monocotyls. 
4. Leaf glands rare and only seen as a 
rule on the sepals. 
5. Water stomata absent or very rare. 
Present in some Aracece. 
6. Palisade and spongy parenchyma 
are less distinct and dense. 
7. The vascular bundles, in their in¬ 
trinsic elements, are less indur¬ 
ated. The fibrous sheath is 
strongly developed. 
8. A comparatively small variety of 
accessory products of assimila¬ 
tion are developed. 
