II SCROPHULARIACEiE 315 



in snowy districts, as they serve to retain small reserves 

 of comparatively warm air ; while the absence of teeth 

 is an advantage in rainy districts, because the wet runs 

 more quickly off a smooth edge. Jungner tested^ the 

 effect of this form on leaves of V. officinalis. In this 

 species the same plant has some entire leaves, some 

 with toothed edges. He chose some smooth and some 

 toothed, and surrounded them by a freezing mixture. The 

 former froze soonest, and melted after the toothed ones. 



V. serpyllifolia. — The flowers are small, pale blue or 

 white, sometimes protandrous, at others homogamous 

 or protogynous. The leaves are glabrous, the stem 

 finely pubescent. 



V. arvensis. — A variable plant ; covered with jointed 

 hairs, arranged on the lower part of the stem in two rows. 



V. agrestis has a pale blue or white corolla, and is 

 pubescent, as is also V. hedersefolia. 



V. spicata. — The flowers are protogynous, blue, or 

 sometimes pale pink, in a dense terminal spike. They 

 open from below, and the undermost are in fruit while 

 the upper ones are still in the bud, so that a spike may 

 show in descending order — buds, flowers in the female 

 state, in the male state, flowers faded, and at the base 

 young fruit. H. Miiller, however, found some plants 

 protogynous, others protandrous. He also found some 

 in which the pistil was rudimentary. The plant is 

 pubescent, and generally slightly glandular. 



V. saxatilis has homogamous flowers, rather large, 

 and bright blue. 



V. alpina, a rare plant, found in the highest Scotch 

 Alps, has flowers homogamous or slightly protogynous, 

 small and blue. The plant is glandular-pubescent in 

 the upper part. 



V. scutellata, not a very common plant, found in 

 bogs and on edges of ditches, is glabrous or glandular- 

 pubescent. 



V. Buxbaumii, a field species, with large bright-blue 

 flowers, is pubescent, but not glandular. 



^ " Klima uud Blatt in der Eegio Alpina," Mora, Ixxix (1894). 



