1921] Pennell, — "Veronica" in North and South America 5 



or recently of man-made, methods of dispersal. Of species natu- 

 rally distributed, Veronica serpyllifolia humifusa and V. Anagallis- 

 aquatica have become nearly cosmopolitan within their respective 

 climates and environments, while carried by human agency and to- 

 day aggressive weeds in our land are Veronica serpyllifolia, V. pere- 

 grina and its variety xalapensis, V. arvensis, V. persica, and V. offici- 

 nalis. To this list, otherwise of Palaearctic origin, America has 

 contributed Veronica peregrina, thus showing that the New World 

 may develop sufficiently aggressive plants. 



I must thank the curators of the United States National Museum, 

 New York Botanical Garden and Philadelphia Academy of Natural 

 Sciences who have placed their rich collections at my disposal. Also 

 I have seen specimens of certain species from the Gray Herbarium. 

 Probably nearly 4000 sheets have been examined in the present study. 

 It has been with hesitation but I trust to the clearing of the problems 

 involved, that I have ventured so freely into Eurasian botany. 



Key to Genera and Subgenera. 



Capsule dehiscing loculicidally, its walls and septum 

 thin. Herbs, the stem dying with the leaves. 

 Corolla white or pinkish, its lobes much shorter 

 than the tube. Capsule acute, longer than 

 wide, not flattened, dehiscing by short apical 

 slits. Seeds slightly reticulate. Plant 10-20 

 din. tall, with leaves in whorls of four or five. 

 Main stem terminating in an inflorescence. . . I. Yeronicastrum 

 Corolla blue or white, its lobes nearly as long as or 

 usually longer than the tube. Capsule aeu- 

 tish to deeply notched, as broad as or broader 

 than long, more or less flattened contrary to 

 the septum, dehiscing by longer slits which 

 extend at times even to the base. Seeds not 

 reticulate. Plants lower, with leaves, at least 

 the lowermost, opposite, or very rarely in 



whorls of three or four II. Veronica 



Main stem terminating in an inflorescence, its 

 flowers remote and axillary or densely 

 crowded, in all cases the upper bract-leaves 



alternate Subgenus 1. Veronicella 



Main stem never terminating in an inflorescence, 

 the leases opposite throughout and the 



flowers all in axillary racemes Subgenus 2. Euveronica 



Capsule dehiscing septicidally, the thick septum 

 splitting and each carpel opening distally by a 

 median slit through the septal wall. Leaves 

 opposite throughout, and flowers all in axillary 

 racemes. Shrubs or small trees, the coriaceous 

 leaves in falling leaving conspicuous scars III. Hebe 



