40 



From what we now know about the cytology of such organisms, 

 it is reasonable to assume that, like so many similar cases, auto- 

 polyploidy' could easily bring about a population of completely 



' AutopoJyploidy — the doubling of the number of chromosomes of a form 

 without prior hybridization ; as contrasted with allopolyploidy — the doubling 

 of the number of chromosomes of an individual the product of hybridization. 

 In either case the resulting forms generally produce sufficient seed to main- 

 tain themselves under favorable environmental conditions. 



Plate 11 



Figures 10a-16c. Linaria vulgaris Hill 



Figures lOa-c, and 11. Normal flowers collected in Bronx Park, New 

 York City, summer of 1940, by C. Gilly. 



lOa-b. External view and floral diagram of a flower with four stamens 

 but with no evidence of the "fifth" ; 10c, median section showing the relations 

 of the internal parts to the spur and particularly the refolded nature of the 

 labium on the lower lip of the corolla; 11, diagram of an otherwise normally 

 appearing flower bearing two anther sacs on the "fifth" stamen much as in 

 Figure 3c. 



Figures 12a-14e. From a series of plants collected by R. Hitchcock, near 

 Van Cortlandt Park, New York City, June, 1909. 



12a-b. External views showing a rare condition in this collection, with 

 five sepals and a small saccate enlargement in place of the spur ; 12c, the 

 corolla laid open showing the four normal stamens and minute supernumerary 

 stamen structures on the lower lip; 12d, further enlargement of the apex 

 of the lower lip of the corolla showing the supernumerary stamen-like struc- 

 tures near its margin. 



13a-b. External views showing the more common condition with four 

 sepals and no evidence of a spur; 13c, the corolla laid open showing the four 

 normal stamens, several well developed stamen structures, and various sessile 

 anther pouches. 



14a-b. External views of a flower essentially similar to the preceding; 

 14c, its corolla laid open to show the position of the supernumerary anther 

 and anther pouches near the margin of its lower lip ; 14d-e, further enlarge- 

 ments of the lateral portions of the lower lip showing details of the super- 

 numerary anther and several anther pouches. 



Figures 15a-c. From a collection by John McCallum, Morris Park, Long 

 Island, New York, in 1912. 



15a-b. Two views of the same flower; 15c, its floral diagram. 



Figures 16a-c. From a collection by Wm. Scott, York Mills, near Toronto, 

 Canada, September 18, 1911. 



16a-b. External views of a flower ; 16c, its floral diagram showing four 

 sepals, four corolla segments, two stamens and the bi-carpelled ovary. 



Figures 17a-b. Veronicastrum virginicum (L.) Farwell 

 From typical material deposited in the Herb. N. Y. Botanical Garden. 

 17a, external view; 17b, floral diagram. 



