INDEX TO AMERICAN BOTANICAL LITERATURE 49 
Neuwirth, M. Vergleichende Morphologie der Trichome an der 
Bliitenteilen der cebras Osterr. Bot. Zeitschr. 66: 141-149. 
pl. 2. 1916. 
Norton, J. B. S., & Chen, C. C. Another corn seed parasite. Science 
IT. 52: 250-251. 10S 1920. 
Nowell, W., & Williams, C. B. Sugar cane blight in Trinidad: a sum- 
mary of conclusions. Bull. Dept. Agr. Trinidad & Tobago 19: 
8-10. 1920. 
Osburn, R. C. The syrphid fly, Mesogramma marginata, and the 
flowers of Apocynum. Ohio Jour. Sci. 20: 261-265. pl zr. 15 ji 
1920. _ 
Parker, F. W., & Truog, E. The relation between the calcium and the 
nitrogen content of plants and the function of calcium. Soil Sci. 10: 
49-56. f. rz. Jl 1920. 
Pearson, W. H. Aplozia Pendletonii Pearson, n. sp. Bryologist 23: 
50-62. D1. 2. 17.5.4020. 
Pemberton, C. G. Living stumps of trees. Am. For. 26: 614-616. 
O 1920. 
Pennell, F. W. Sask of Colombia I. Proc. Acad. Nat. 
sa ee Pe 1920: glass _ O se 
des Monocardia and Unanuea, gen ,an species in Caconapea (3) 
Pes ne Monocardia (4), Prete (1), eile: a  Waaate (10), Russelia (1). 
* Pilger, R. Plantae Uleanae novae vel minus cognitae. Notizbl. Bt.o 
Gard. und Mus. Berlin-Dahlem 6: 485-503. 15 Ja 1917. 
Includes Piperaceae and Meliaceae by C. de Candolle, here indexed separately. 
Pittier, H. La evolucién de las ciencias naturales y las exploraciénes 
botanicas en Venezuela. Cultura Venezolana 14: (Suppl.) 1-28. 
1920. 
Prankerd, T. L. Statocytes of the wheat haulm. Bot. Gaz. 70: 148- 
152. f. 1-4. 21 Au 1920. 
Quehl, L. LEchinocactus Rettigii Quehl spec. nov. Monatschr. 
Kakteenk. 29: 129. N 1919. 
rom Peru. 
Reed, G. M. Varietal resistance and susceptibility of oats to powdery 
mildew, crown rust and smuts. Missouri Agr. Exp. Sta. Research 
Bull. 37: 3-41. pl. 1-4. Jl 1920. 
Reed, H.S. The dynamics of a fluctuating growth rate. Proc. Nat. 
Acad. Sci. 6: 397-410.. 15 Jl 1920. Ne 
Growth of apricots studied. - 
ton, J. The cocoa-nut palm. Am. Forestry 26: $2053 a 
1920. [Illust.] i 
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