4-8 THE PLANT WORLD. 



strap-shaped or linear petals appear, but as the season advances the 

 petals of later flowers grow broader and more numerous until the 

 latest ones are as complete and well developed as those in early spring. 



Many other violets with the same habitat complete this cycle each 

 season. Others, like the Canada violet, produce showy flowers 

 throughout, but this is usual only in cool, damp ravines. In cultiva- 

 tion, unless these conditions are simulated, the plant blooms only in a 

 desultory way, if at all, or it may produce cleistogamous flowers. 

 Nor is such phenomena confined to our own coimtry. It is said that 

 F. Roxburghiaiia^ a native of India, bears perfect flowers only during 

 the cold season. When Darwin tried to raise them under glass the 

 showy flowers ceased, but an abundance of cleistogamous ones ensued. 

 It is likely that many such instances could be collected. Florists find 

 that to produce perfect flowers of the sweet violet only a small amount 

 of heat inust be applied, a further raise in temperature dwarfing the 

 flowers. And growers of pansies know that during the hot weather 

 the flowers incline to be small and weak unless the plants are in situ- 

 ations where shade and moisture make a lower temperature. 



Additional light is thrown on the subject when we come to exam- 

 ine the geographical distribution of the violets. They are usually 

 found in the temperate parts of the earth, and even then the moun- 

 tains, deep ravines and the cool borders of streams are their chosen 

 haunts. These instances would seem to prove the truth of my 

 theory, independent of the fact that we may actually see the cleisto- 

 gamous flowers change to showy ones. 



Professor Lester F. Ward has just published an elaborate paper 

 in the Proceedings of the U. S. National Mnsenin on the fossil 

 Cycadean trunks thus far determined from the Lower Cretaceous 

 rim of the Black Hills. It contains descriptions of twenty-one 

 species, all but one of which are regarded as new to science, and is 

 based on 155 specimens. We hope to present one or more plates of 

 these fossils, together with a brief popular account, at an early date. 



The discovery of a new rose by Mr. E. O. Wooton in New 

 Mexico, which has but one species in the whole world closely allied 

 to it and that species, Rosa ininutifolia, having been found only in 

 Lower California, has aroused much interest abroad among rose 

 specialists. M. Crepin, who has made a life study of this genus, has 

 published some critical comparisons of the two species in the Bulletin 

 of the Boissier Herbarium. He finds some marked differences be- 

 tween the two species, but concludes that the new one, R. stellata, 

 has been properly placed in the section with the small-leaved rose. 



