^ 



^ 1907] CURRENT LITERATURE 153 



NOTES FOR STUDENTS 



f Recent anatomical papers. — A very detailed account of the leaf structure of 



^ • American Lauraceae has been given by Petzold,5 his purpose having been to 



establish at least generic anatomical characters. The leaf structure, however, 

 proves to be quite uniform, and generic distinctions are not feasible. For 

 example, a concentric structure is characteristic of Silvia, but occurs also in a few 

 species of Phoebe and Nectandra; a hypoderm is developed in Cryptocarya and 

 Hufelandia, but also in some species of Ocotea, Persea, and other genera; a 

 closed sheath of stereome surrounds the veins constantly in some genera, but not 

 in others; crystals of calcium oxalate, otherwise so frequent in this family, do not 

 occur in Lindera and DicypelHum, but they are also absent in several species of 

 other genera. The paper is a welcome contribution to the knowledge of the 

 anatomy of these plants, even if no generic characterization seems possible. 



The structure of leaves, seeds, and pollen of Polemoniaceae have been 

 examined by Huller,^ his material including a large number of American 

 species. It deserves mention that calcium oxalate was detected in certain 

 species of Collomia and Gilia as single cr}'Stals, and as druids in the monotypic 

 Bonplandia. The stomata were always observed to lack subsidiary cells, thus 



» agreeing with the type of Ranunculaceae. Trichomes as covering-hairs and as 



glandular hairs are very common, representing several characteristic forms. In the 



^ midrib of Phlox Dnimmondii and various species of Gilia, the mestome strand 



contains two or sometimes several groups of leptome. 



In regard to the structure of the seed coat, Phlox is the only genus in which the 

 epidermis contains mucilage only in the outer wall beneath the cuticle. The 

 peculiar spirals of cellulose were noticed in most species of all genera except 

 Phlox. Inside the epidermis there are usually some strata of compressed tissue 

 and a pigment layer; but in Cobaea a fourth tissue was absent, namely, w^oody 

 parenchyma beneath the epidermis. The nutritive tissue, which is relatively 

 sparingly developed, contains oil and aleurone. 



The pollen grains are globose or elliptic, and the exine is never smooth, but 

 covered with protuberances in the shape of ridges or granules in numberless 

 variations. There are always more than three germ-pores, from four to many, 

 and in some cases scattered irregularly over the surface. Although the author 

 had to depend upon dried specimens, the results are nevertheless quite interesting 

 and of importance to systematic anatomy. However, a study of fresh material, 

 including the stem and root, would be highly desirable. 



Forty-three species of Meliosma (Sabiaceae) have been examined by 

 DiHM.' The palisade tissue is verj' characteristic in representing a modification 



5 Petzold, v., Systematisch-anatomische Untersuchungen iiber die Laub- 

 blatter der amerikanischen Lauraceen. Bot. Jahrb. 38:445-474- I9^7- 



^ HtJLLER, G., Beitrage zur vergleichenden Anatomic der Pulemoniaceen. Beih. 

 Bot. Centralbl. 21^:173-244. pL 8. figs, 25. 1907. 



7 DiHXf, II., Das Blatt der Gattung Meliosma in anatumischer Hinsicht. Bcih- 

 Bot. Centralbl. 211:117-147. pis. 5-6, figs, 21. 1907. 



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