FIELD AND LABORATORY STUDIES OF VERBENA 



CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 267 



M. K A N D A 

 (WITH PLATES VI-IX AND TWENTY-SIX FIGURES) 



Introduction 



In Gray's New Manual of Botany (edition of 1908), 8 species 

 of Verbena are described as occurring in the Eastern United States. 

 These are classified into two sections, of which the first is further 

 subdivided into three groups. Five of the 8 species grow wild in 

 the vicinity of Chicago, namely, Verbena urticaefolia L. and 

 V. bracteosa Michx., belonging to the first and third groups respec- 

 tively, and V. angustifolia Michx., V. hastata L., and V. stricta 

 Vent, to the second group. These three last named species occur 

 abundantly at Stony Island, a southern suburb of Chicago, where 

 the conditions of prairie, damp, and dry ground are met with 

 successively as one proceeds from the north to the south end of 

 the locality. Here the three forms grow in their characteristic 

 ecological situations: V. stricta on the prairie, V. hastata in damp 

 low places, and V. angustifolia on high dry ground. On examining 

 the Verbena plants, one is rather surprised to find that there are 

 many intermediate forms which can scarcely be assigned to any 

 of the three species with certainty. The question arises, therefore, 

 as to whether they are hybrids or mutants of the three species. 



The present work was undertaken to determine whether or not 



o there are any cytological differences in the fertilization phenomena 



and early stages of development between these forms. The results 



were rather negative as regards the genetic nature of the intermedi- 



l ate forms; that is, with slight exceptions, no significant differences 



q_ were found between them. Many of the observations upon the 



'^ embryonic development, however, are sufficiently interesting to 



merit description. These will therefore constitute the chief subject 



-_t§atter of the present paper, such facts and suggestions as I am able 



p £0 present regarding the origin and nature of the intermediate forms 



I feng added at the close. 



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. Botanical Gazette, vol. 69] 154 



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