22 



spicate inflorescence. The presence of buds at the apex of the 

 section signifies that such elongation must have preceded flower 

 formation and hence have been an early growth of the meriste- 

 matic tissue; an evidence of a change in organization rather than 

 an adaptive variation. 



The interest awakened by these specimens stimulated further 

 collections in other localities in the fall months of 1920. Plants 

 with conical and oblong heads were collected at various points in 

 Highlands, N. J. These plants were growing in gravelly soil on 

 hillsides at some distance from the beach. 



Fig. I was drawn to scale from a lengthwise section of a normal 

 head with a flat receptacle. The projection of tubular flowers 

 beyond the marginal ray flowers is less than one mm. in the flat 

 receptackd forms. The external view of a head shown in Fig. 2 

 and the lengthwise section in Fig. 3 are of an example on another 

 branch of the same plant where the prolongation of the head 

 beyond the involucre was 4 mm. There were from 23 to 2'] 

 flowers in these heads while those with the flat receptacles aver- 

 aged 12 flowers in a head. In all examined it was found that the 

 elongation of the receptacle resulted in an increase of perfect 

 flowers and hence of fruits. It has been shown by various in- 

 vestigators as reviewed by Stout and Boas* in their statistical 

 studies of Ciclioriiiui that number of flowers ])er head varies with 

 the position in the inflorescence. With Achillea it would appear 

 that the form of the receptacle is a governing factor. 



Two weeks later when on a collecting trip in the Edenwald 

 section of the Bronx plants were found possessing receptacles 

 with a much greater elongation. Figs. 4 and 5 are of one from 

 this locality. Expressing the measurements in order of proximity 

 of heads in a corymb, the elongation of the receptacles are as 

 follows in mm. : 7, 7, 7, 6, 6, 8, another 8, 9, 11, 11, 10, 11, 10, 10, 

 7, 9, in another 10, 9, 10, 10. 11, 11, with six succeeding of 10 mm. 

 Another branch had corymbs with 4 adjoining heads of 10 mm., 

 7 of 9 mm., with the remaining ones of 8, 8, 9, 9, 8 mm. It is to 



* Stout, A. B., and Helena M.Boas, Statistical Studies of Flower Number 

 per Head in Cichorinm intybus N. — Kinds of Variability, Heredity and Effects 

 of Selection, Mem. Torrey Bot. Club: 17. 334-458, 1918. 



