1876.J 



AND HORTICULTURIST. 



369 



ATURAL fMlSTORY AND fSClENCE. 



EDITORIAL NOTES. 



Rainfall and Forests. — Our European friends 

 are finding some curious " facts " in regard to 

 rainfall and forests. In France, a Mr. Fautral 

 found that there was much more rain fell in a 

 forest than on a sandy plain not a great way 

 from it. It so happened, however, that another 

 forester kept an account in a forest about the 

 same distance from the sandy plain, and the fig- 

 ures from the two forests do not agree. Most 

 persons would have suspected an error in ascrib- 

 ing much influence to the forests, but these two 

 fell to discussing the nature of the forests them- 

 selves; and now it is asked of us to believe, that 

 while ten per cent, more rain will fall on a pine 

 forest than on a sandy plain, only five per cent, 

 more falls on an oak one ! The only wonder is 

 that 95 per cent, should fall on the treeless plain. 



On the Diurnal Opening of Flowers.— 

 At a recent meeting of the Academy of Natural 

 Sciences of Philadelphia, Mr. Thomas Meehan 

 referred to observations he had made this season 

 on the nocturnal and diurnal expansion of flow- 

 ers, and said that, contrary to the popular im- 

 pression, it was not probable that light or its ab- 

 sence alone determined the opening of the blos- 

 soms. There were some plants, as for instance 

 CEnoth era biennis, the Evening Primrose; Anagal- 

 lis arvensis, the "Pimpernel," and others which 

 remained open or otherwise longer when the 

 weather was humid or clear, and were looked on 

 in consequence as kinds of floral barometers; but 

 from other facts it was clear that it was not the 

 weather merely, but some other incident accom- 

 panying the weather that governed the case. 



For instance, though Oenothera biennis, and 

 other CEnotheras opened at evening, — and if the 

 atmosphere be moist, would continue open 

 the greater part of next day. — many species 

 opened only in the day time, and this they did 

 regularly quite regardless of "meteorological con- 

 ditions. CE. serrata, of Colorado, was one of 

 these. It was regular in opening about noon, 

 and the blossoms were all closed long before sun- 

 down. 



In other allied families, we saw similar di- 

 vergencies. In the Cactus family, Opuntia and 

 Mammillaria opened only about mid-day; while 

 most of the Cereus opened at night. The night- 

 blooming Cactus was a familiar example. But 

 the chief interest was in the fact that many had 

 their special hours of day or night for the ex- 

 pansion. The Portulacca oleracea, common 

 Purslane, opened about eight a. m.. and by nine 

 had performed all its functions; while a closely- 

 allied plant, the Talinum teretifolium, from the 

 serpentine rocks of Chester County, opened at 

 one p. M., and was closed by three. The con- 

 ditions of the weather did not seem to influence 

 them. 



There was the same attention to daily periods 

 in the growth of the parts of plants, as well as in 

 the expansion of the petals. In composite plants, 

 the floral growth was generally in the morn- 

 ing, and was usually all over by nine or ten 

 o'clock a. m. The elongation and expansion 

 of the corolla was usually completed in an hour 

 after sunrise; but the stamens grew for an hour 

 more, and the pistil continued for still another. 

 There was little if any growth in the floral parts 

 after nine o'clock in a very large portion of this 

 order of plants. In grasses, Cyperacese, and 

 some rushes, the floral parte were very ex- 

 act in their time of opening. In the Plantains 

 (Plantago) the pistils appeared a day or more in 

 advance of the stamens, and these last appeared 

 at about a regular time in each day. In Luzula 

 campestris, the wood form, he had by a series of 

 observations timed it exactly. Before nine the 

 anthers were perfect, but by ten the pollen has 

 been all committed to the winds, and only dried 

 membraneous matter remained. So far as he 

 could ascertain, meteorological conditions did not 

 influence the time in the least in this case. 



The popular impressi(m of light and moisture, 

 as agents in this behaviour, had seemed to 

 receive a tacit scientific assent. It was clear he 

 thought there was a more powerful agency un- 

 derlying these, and it was perhaps a gain to 

 science to be able to see this, though in so dim a 

 light. 



