lU Univcrsilij of Calif urn ia Publications in Botany [Vol. 7 



cliloniplast coloration alone An investigation from this p<iint of view 

 ol' the nalni'i' ni' tin- vai'ions coloi's concerned is in ])rogress. 



These color forms which seem to be rather strikingly peculiar to 

 certain definite localities might appear superficially to correspond 

 to one anotlit'i' in cliai'acli'rs which are of more significance from the 

 point of view of specific differentiation — i.e., size and form characters 

 of vegetative and fioi-al organs. We feel rather certain, however, 

 that more exact (juantitative studies will, in some cases at least, 

 reveal correlation between color and other characters, the sura total 

 giving sufficient differentiation fi-om all other forms possibly to 

 indicate specific definition and to warrant specific description. With 

 this in mind we have measured all significant structures whenever 

 collections have been made. The criteria of specific differentiation 

 in the genus Trillium are not such that simple size differences of 

 vegetative or floral organs, or even proof that the correlation in size 

 of organs is different in the various color forms, will give convincing 

 evidence on relationships. Such evidence will depend upon demon- 

 stration of shape and form differences, and thus it is desirable to 

 find a method according to which the measurements of size of organs 

 can be used in expressing their shape. It is also highly desirable 

 that the tentative use of the combination T. sessile var. giganteum 

 which later on may seem best changed to T. giganteum, both repre- 

 senting efforts to recognize the size distinction between eastern and 

 Californian sessile forms, be placed upon a demonstrable basis. It 

 is thus planned to compare the size differences of these geographically 

 distinct sessile species, and until this is done we do not propose, as 

 noted above, to present the statistical data at hand. 



Rootstocks of T. sessile var. giganteum were first brought into 

 the University of California Botanical Garden in the spring of 1911. 

 In February, 1916, the total number of rootstocks under observation 

 was nearly 150. We have data on sixty plants over a period of six 

 years and on forty plants over a period of four or five years, while 

 the remainder were introduced into the cultures after 1913. The 

 various localities where, as mentioned above, field studies were made 

 are practically all i'ej)resented by rootstocks in the Garden. In May, 

 1914, we secured rootstocks of T. sessile L. from New Lennox, Illinois, 

 and rootstocks of T. grandiflorum (Michx.) Salisb. from Sawyer. 

 Michigan. During the past two growing seasons we have had a 

 few flowering and a number of flowerless shoots from these rootstocks. 

 From time to time a few rootstocks of T. ovatum Pursh. have been 



