310 CARNEGIE INSTITUTION OF WASHINGTON. 



insufficient evidence. Many of these segregates seem generically distinct 

 when considered locally, but their maintenance becomes impossible when all 

 of the connecting species are assembled from the entire range of the genus. 

 The most logical and useful treatment, therefore, is to accept Haplopappus in 

 approximately the sense of Bentham and Hooker and of Gray, but with 

 certain readjustments between it and related genera, especially Bigelovia and 

 Chrysothamnus, these changes being necessary in order to establish the groups 

 upon a phylogenetic basis. The natural subgenera, all of which have been 

 given generic rank at one time or another, are : Hazardia, Isocoma, Ericameria, 

 Pyrrocoma, Isopappus, Stenotus, Macronema, Tonestus, Prionopsis, Oreo- 

 chrysum, and Oonopsis. A phylogenetic arrangement of these has been pre- 

 pared, and their relation to other subgenera of South America has been 

 indicated. A full taxonomic account of the species, subspecies, and minor 

 variations, based upon field, experimental, and statistical studies, is now in 

 progress. 



Taxonomy of the Madiece, by H. M. Hall. 



This subtribe of the Compositae is restricted almost entirely to the Pacific 

 Coast of North America. It is, therefore, especially suitable for garden 

 experiments carried on within this area and, since the species are accessible 

 for field and statistical studies, the group is an ideal one for intensive phylo- 

 genetic investigation. Garden cultures started some 10 years ago are now 

 undergoing considerable extension. During the autumn of the present year 

 seeds of about 50 forms were collected in various parts of California. These 

 will be used in greenhouse and garden experiments designed to test the nature 

 of characters employed in the classification of the genera, species, and smaller 

 taxonomic units. 



Dr. M. C. Mann, of the Division of Genetics, University of California, has 

 studied the chromosomes of 6 forms grown in the botanical garden and reports 

 12 pairs each for Hemizonia congesta, H. rudis, H. lutescens, H. citrina, and 

 H. grandi-flora, but 10 pairs for H. corymbosa. This tends to support the 

 taxonomic view, arrived at through field and cultural studies, that all five 

 species first named are very closely related and perhaps to be treated as 

 subspecies and minor variations of //. congesta, the earliest name for the 

 group, while H. corymbosa belongs to a different subgenus. 



Rubber Plants, by H. M. Hall and Frances Long. 



A revived national interest in the rubber situation has led to cooperative 

 arrangements with the United States Department of Agriculture for the 

 study of native rubber plants. Special attention is being given to species of 

 Chrysothamnus and Asclepias recently discovered to contain rubber, as 

 reported in earlier editions of the Year Book. Plans for experiments have 

 been formulated and these are now being carried out by the Department's 

 representatives at Fallon, Nevada, for Chrysothamnus, and at Bard, Cali- 

 fornia, for Asclepias subulata. The numerous subspecies and minor variations 

 of C. nauseosus are being rapidly assembled at the former station with a view 

 to utilization in breeding and selection and for the study of their behavior, 

 especially as regards rubber-content under different ecological conditions. 

 Wherever possible, the forms are introduced both by means of seeds and 

 through the transplanting of individuals. In the latter case, detailed records 

 are preserved for each individual, so that any change in its characters may 



