92 THE POPULAR SCIENCE MONTHLY. 



stems and leaves. The silver-maple plantlet is pulpy and already of a 

 deep green when it falls from the tree, and probably is killed as soon 

 as it becomes thoroughly dried. The seed runs many risks for the 

 sake of being a sizable seedling the same season. 



The box-elder (Negundo aceroides, Moench) belongs to a most 

 closely related genus to the maples, and by some botanists it" is placed 

 with them in the genus Acer. The most striking difference is seen 

 in the leaves, those of the box-elder being compound like the ash, hence 

 one of the common names, "ash-leaved maple," while the leaves of the 

 familiar maples are simple. In the box-elder the sexes are separated 

 much more clearly than in the maples. One tree bears only staminate 

 flowers while another has only pistillate blossoms, and therefore bears 

 the fruit. To have good seeds it is necessary that at least two box- 

 elder trees be in the same vicinity, and one of these must be male and 

 the other female. This tree is the type of hardiness in the severe 

 climate of the Northwest, but in this connection there are some points 

 not easy of explanation. The box-elder of one section of the country 

 may be identical- in structure with specimens in a different climate, 

 but widely different in hardiness. This brings to view again the law 

 of adaptation as applied to the inherent ability to withstand the un- 

 toward circumstances that have surrounded the ancestry for long 

 periods in the past. The same is true of many other species growing 

 over wide areas of country. They may possibly retain the same bo- 

 tanical characteristics, but beyond all that the eye, with the aid of the 

 best microscopes, can see, there is that which enables one plant to 

 flourish when another will fail. 



The 17th of April brought blossoms of Caltha 2)cdustris (L.), and 

 Carex stricta (Lam.). The first is the marsh-marigold, or perhaps 

 more familiarly known as the "cowslip." The genuine cowslip of 

 the poets is a different plant, it being a primrose. The caltha is a 

 pot-herb of no great merit, and does not possess that type of beauty 

 which inspires the muse. The carex is the second sedge of the season. 

 It doubtless has its place to fill in the scheme of creation. 



April 18th introduced us to three species, the Pojndus monilifera 

 (Ait.), or cottonwood ; Antenaria planiagini folia (Hook), the plan- 

 tain-leaved everlasting ; and Viola palmata, var. cucidlata (Gray), the 

 common blue violet. Spring has now fairly opened, for the violets 

 have come. This day throws together in the list three very different 

 plants. The poplar is one of the most wide-spread and hardiest of 

 trees. It is the only kind of arboreal vegetation in many places 

 along water-courses of the Northwest, in regions subject to severe 

 climatic conditions. It can bear the heat and drought of summer and 

 the extreme cold of winter when other forms succumb. It may be 

 worthy of note that this hardy tree produces timber that is among the 

 lightest on the list of woods in the United States. Its specific gravity 

 is only .388G, or a little more than one third as heavy as water. We 



