BREEDING SNAPDRAGONS 13 



species of Antirrhinum native to California and some success in inoculating 

 related genera. The reports of Dr. J. C. Arthur confirmed the observations of 

 Blasdale (1) who has suggested that rust {Puccinia antirrhinum Diet. & Holw.) 

 was indigenous on species of Antirrhinum in California. Peltier (10) reported 

 successful inoculation of a number of commercial varieties of snapdragons {A. 

 majus Linn.) but was not successful in obtaining infection of a number of species 

 of Antirrhinum or varieties of Linaria vulgaris Mill, (common butter-and-eggs) 

 which is a genus related to the snapdragon. 



At Waltham, 56 different wild species and strains of Antirrhinum were tested 

 in the field for reaction to rust disease. In several Instances, because of low germi- 

 nation and lack of seed, the number of plants was not adequate for analysis as 

 to rust resistance of some of the species. 



Susceptibility to rust was found to be variable In many of the species of Antir- 

 rhinum studied. This was particularly noticeable where a sufficient number of 

 plants within a species was available for testing. Seven out of twelve strains of 

 A. majus Linn, were highly susceptible and five showed a moderate degree of 

 resistance. A. glutinosum Boiss. contained strains that were rather variable, 

 with four forms highly resistant to rust and others in which Individuals exhibited 

 a wide range of susceptibility. The species most outstanding in uniformity of 

 rust resistance was A. calycimim, a white-flowered, low-growing type of snap- 

 dragon. The majority of species and forms tested for rust resistance produced 

 plants which were predominantly low or prostrate in habit of growth. 



Species of Antirrhinum found most outstanding in resistance to rust at Waltham 

 were: 



A. glutinosum Alhama (Behaart) A. Charidemi Lge. 



A. glutinosum Alhama (Kahl) A. calycinum 



A. glutinosum Geniltal A. Ibanjezii Pau. 



A. glutinosum Baryacas A. siculum NCZ 



The data on reaction of wild species and strains of Antirrhinum to rust diseases 

 are not entirely in accord with observations reported by other investigators. 

 Emsweller and Jones (4) noted resistance In A. glutinosum, A. hispanicum, A. 

 Ibanjezii, A. molle, and A. siculum. Their results were substantiated by Mains 

 (9), who records A. asarnia, A. Ibanjezii, A. maitrandioides, A. vtrgo, and strains 

 of A. glutinosum as highly resistant to rust, but A. Orontium as only moderately 

 resistant. At Waltham A. Orontium and A. chrysotJmles were highly susceptible 

 to rust (Table 6); whereas Blodgett and Mehlqulst (2) reported these same species 

 as among the most outstanding species resistant to rust in California. 



Although the response of all the Antirrhinum species to rust, as reported by 

 investigators, Is not consistent, there Is agreement as to the reaction of A. siculum 

 and A. Ibanjezii, but some reservations with respect to A. glutinosum. Critical 

 inspection of data presented on the response of Antirrhinum species and strains 

 to rust dise.' se indicates that species received by the several workers under the 

 same specific name may not be Identical. Blodgett and Mehlqulst (2) state that 

 several of their strains of A. glutinosum, A. Ibanjezii, and A. Barrelieri were of 

 doubtful identity. Definite determinations of the identity or relationship of a 

 number of species, and disseminations of these from one standard sample to 

 workers In several geographical areas for testing, would eliminate much uncer- 

 tainty as to whether the same strains were being tested. Apparently the inter- 

 crossing of species of Antirrhinum with commercial varieties has not proved 

 entirely satisfactory, as many of the species do net interbreed readily because of 

 sterility. 



