274 ■ BOTANICAL GAZETTE [march 



of the apical region of the phyllode and not homologous with the blade of a 

 dicotyledonous leaf. Such a blade among monocotyledons Mrs. Arber calls 

 a "pseudo-lamina." Such theories have been devised to explain the parallel 

 venation of monocotyledonous leaves. Attention is also called to Gray's 

 suggestion that some gymnosperm leaves may be equivalent to petioles, and 

 the further suggestion made that this may be applied specially to the Gnetales. 

 These views were tested by Mrs. Arber in anatomical investigations, 

 comparing scale-leaves, petioles, and phyllodes of dicotyledons with the leaves 

 of monocotyledons, the conclusion being reached that the occurrence of inverted 

 vascular bundles toward the adaxial face of a leaf may be an indication of 

 "phyUodic morphology." Other indications of phyllodic anatomy are devel- 

 oped, and its systematic distribution shows that it does not occur with any 

 frequency outside the Helobiae, Liliiflorae, and Farinosae. This distribution 

 is taken to confirm the view that phyllodic anatomy is an ancient character, 

 reveaUng the origin of the monocotyledonous leaf. — J. M. C. 



Stomata. — Rehfous" has published a detailed study of the stomata of 

 many groups. The details are too numerous for citation, but some of the 

 general conclusions may be indicated. He is convinced that stomata are of 

 first importance in indicating phylogeny and relationships. Their structure he 

 claims is very constant within a group, numerous examples of this being given. 

 For example, the structure of the stomata of the Amentiferae shows that they 

 are nearer the level of the dicotyledons than of the gymnosperms or pterido- 

 phytes. In the same way it is shown that the Polypodiaceae constitute a 

 special group, and that the Osmundaceae, Gleicheniaceae, and Schizeaceae 

 approach more nearly the higher plants. A close resemblance is found between 

 the stomata of cycads and conifers, leading to the conclusion that these groups 

 are of common origin. Numerous illustrations of claimed relationships within 

 great groups are either confirmed or contradicted. Several new types of sto- 

 mata are described, among which those of Polypodium, Platyceriiim, Cycas, 

 and Casuarina may be cited. In connection with the last named genus it is 

 pointed out that its stomata are related to those of certain monocytoledons, as 

 the grasses and certain of the xerophytic Liliaceae. The contribution is a 

 valuable assemblage of facts in reference to the structure of stomata, accom- 

 panied by clear illustrations. The conclusions drawn from these facts are open 

 to discussion. — J. M. C. 



Water conduction in trees and shrubs. — Farmer" has pubHshed the results 

 of an investigation of the comparative efficiency of the wood as a water- 

 conducting tissue in about 60 species of plants, chiefly trees and shrubs. The 



" Rehfous, Laurent, Etude sur les stomates. Univ. Geneve, Inst. Bot. IX, 

 no. 6. pp. no. figs. 125. 191 7. 



" Farmer, J. Bretland, On the quantitative differences in the water-conductivity 

 of the wood in trees and shrubs. Proc. Roy. See. B. 90:218-250. 1918. 



