30 



Erigeron anmms and Medicago lupuliua are generally classed as 

 annuals, they are regularly biennial in New York alfalfa fields. 



While the appearance of the hibernating dodder is such that 

 there seems little reason to doubt that it really is alive and capa- 

 ble of further growth, the writers have thought it best to place 

 the matter beyond question by forcing the threads into growth. 

 This has been accomplished several times by placing the dodder- 

 infested crowns in a moist chamber for a few days. Given warmth 

 and moisture the dodder threads begin to lengthen promptly. 

 In six such experiments the dodder-infested crowns were placed 

 in contact with thrifty young alfalfa plants growing in pots in a 

 moist inoculation chamber in a greenhouse. In every case the 

 dodder started promptly, established itself on the alfalfa plants 

 and there made a vigorous growth. 



Our observations have been confined to the State of New 

 York ; but dodder hibernates there so frequently and under such 

 a variety of conditions as regards soil and exposure, that we can 

 but believe that it is perennial also in other parts of the United 

 States. 



Whether other species besides Cuscuta Epitliymmn are peren- 

 nial, we cannot now say. In every instance in which the identi- 

 fication of the dodder has been made possible by the appearance 

 of flowers, the species has been found to be C. Epitliynmni. 

 Agricultural Experiment Station, 

 Geneva, New York. 



NOTES ON SAGITTARIA 



By Kenneth K. Mackenzie 



Almost all American botanists are acquainted with the com- 

 mon arrow-head [Sagittaria latifolia Willd.), and are familiar with 

 the great amount of variation in the shape of its leaves. These 

 are ordinarily strongly sagittate, but they vary from several inches 

 broad to but two or three millimeters. All botanists are, how- 

 ever, thoroughly agreed that these variations, while striking, are 

 of no importance from a systematic standpoint, but depend en- 

 tirely on the conditions under which the plant has grown. This, 

 then, being the thoroughly understood condition with reference 



