392 



Garden and Forest. 



[Number 397. 



to kindle into the glowing- colors of the parent stock. 

 Would it not be well for nurserymen to find practical an- 

 swers to such questions as this ? Such experiments mig-ht 

 be carried still further, and a test could be made with trees 

 propagated from an individual branch whose foliage is 

 known to change every year at an earlier period or to 

 a brighter color than is the case with the rest of the tree. 

 Here are deOnite points inviting study, and the facts which 

 are ascertainable might help us to enhance the beauty of 

 our parks and gardens for several weeks every j^ear. 



tree, as it grows in its best estate, familiar to many of our 

 readers, but the illustration on page 395 of this issue, made 

 from a photograph for which we are indebted to Dr. W. 11. 

 Rollins, of Boston, shows the habit of a group of several 

 young trees of this species, probably one hundred feet high, 

 growing in the Yosemite Valley. 



Pinus ponderosa. 



THE Western Yellow Pine, or Pinus ponderosa, is the 

 most widely distributed Pine-tree of the mountain 

 forests of western North America, where it is distributed from 

 the interior of British Columbia, from about latitude fifty- 

 seven degrees north, southward to Mexico and eastward 

 to northern Nebraska, the foot-hills of the Rocky Mountains 

 of Colorado, and western Texas. Usually an inhabitant of 

 dry elevated slopes, where it often forms open forests of 

 great extent, it flourishes also on the western slopes of the 

 Sierra Nevada, in the comparatively humid climate of 

 northern California, where it attains its largest size, and in 

 California also grows occasionally in wet and swampy 

 ground. It is the only Pine-tree of Nebraska, and is very 

 abundant on the Black Hills of Dakota ; in northern Mon- 

 tana it forms a great forest in the valley of the Flat Head 

 Lake and ranges westward to the shores of Puget Sound ; 

 it dots the slopes of the eastern foot-hills of the Rocky 

 Mountains of Colorado, and clothes the divide betvi'een the 

 Platte and Arkansas rivers with a forest pushed far out over 

 the plain. Abundant in similar situations in Utah and 

 common on the eastern slopes of the Sierras, where it 

 attains a great size and beauty, Pinus ponderosa has found 

 the climatic conditions of the Great Basin too severe for it. 

 and it does not occur on the mountain ranges of central 

 and southern Nevada. The Colorado plateau, which has 

 an area of many thousand square miles in southern Colo- 

 rado and Utah and in northern Mexico and Arizona, is 

 covered with a forest of this tree. This is now the greatest 

 uninterrupted Pine forest of the continent, and probably the 

 largest in the world. South of the Colorado plateau the 

 desert is broken up into short ranges of mountams, and on 

 them, on both sides of the Mexican boundary, Pinus pon- 

 derosa is a common tree, as it is on the mountains of west- 

 ern Texas. A tree of such enormous range over a region of 

 so many different climates has naturally developed many 

 forms, and no other American Pine-tree varies more in size 

 and habit, in the character of bark, length of leaves and 

 size of cones. Sometimes it is fully three hundred feet tall, 

 with a trunk fifteen feet in diameter, covered with bright 

 cinnamon-red bark, broken into great plates, and some- 

 times it attains with difficulty the height of fifty feet, and its 

 bark is nearly black and deeply furrowed. Such variations 

 in the character of the bark are not always due to climate, 

 however, and individuals with the red bark of the Califor- 

 nia tree and the black bark of the inhabitant of the arid 

 slopes of the Colorado Mountains stand side by side in 

 northern Arizona to the discouragement of the botanist 

 anxious to understand this tree and the causes of its varia- 

 tions. 



One hundred photographs would not be too many to prop- 

 erly illustrate the appearance of Pinus ponderosa in the dif- 

 ferent parts of the country which it inhabits, and an attempt 

 to describe its different forms with any words at our com- 

 mand would be hopeless. Certain characters which 

 botanists consider valuable specifically can be found in all 

 the forms, so that it is most convenient to consider them 

 all geographical varieties of one species, although in size 

 and general appearance and in the character and value of 

 the timber produced they are as distinct as many of the 

 recognized species of our Pines. 



The beautiful photographs of the Sierra forests often seen 

 in the east have, no doubt, made the appearances of this 



Autumnal Changes in Leaves. — II. 



A (jREEN leaf, or an alcoholic extract of one, viewed 

 /\. through a spectroscope, shows a band of light, or spec- 

 trum, which is very characteristic ; its dark intervals or ab- 

 sorption bands, resembling those of no other substance. 

 If, now, we mix benzine with our green solution of chloro- 

 phyll which we have obtained by soaking, say. Elm leaves 

 in alcohol, the liquid separates into two layers, the upper 

 of bluish-green benzine and the lovi^er of yellow alcohol. 

 These two solutions give different spectra, proving them 

 different substances. Our chlorophyll, then, was a mix- 

 ture of at least two substances, or, more likely, a chemi- 

 cal compound which broke into two of its constituent 

 compounds, the yellow one being called xanthophyll. 

 Now, this separation presumably occurs when green 

 leaves turn yellow, as is suggested by a simple experi- 

 m:ent. If our alcoholic extraction from Elm leaves 

 has not been kept in darkness and sealed from the 

 oxygen of the air, it has rapidly decomposed, turning from 

 green to yellow — that is, the green constituent fades away 

 first, gradually revealing the yellow one which, by the way, 

 some consider the equivalent of theetiolin that always pre- 

 cedes the first formation of the green pigment. 



Chlorophyll, however, is not simply reducible into two 

 components, a green and a yellow, but into several more 

 which it might be tedious and confusing to describe in 

 detail. Over a score of distinct pigments exist in leaves. 

 We may say, though, that an acid added to our original 

 bright green extract turns it to a dull yellowish-green 

 solution giving a new spectrum, and the same change, 

 doubtless, occurs in the Grape leaf and others naturally 

 containing free acid. 



Returning once more to our alcoholic solution of chloro- 

 phyll, let us evaporate it to a green residue to which we 

 will add water. The water dissolves out a gold-yellow 

 substance which cannot be erythrophyll, for that is insolu- 

 ble in water, besides having a different spectrum as well as 

 another shade of yellow. This gold-yellow substance, 

 vi'hose name we had better omit, is very prevalent in au- 

 tumnal leaves of Elm, Poplar, Milkweed and many more, 

 occurring in four or five varieties, as distinguished by their 

 optical properties. It is not always found, though, whereas 

 xanthophyll invariably accompanies chlorophyll. A solu- 

 tion of this gold-yellow pigment in water may readily be 

 oxidized by artificial means into substances with different 

 shades of brown, and the oxygen of air, doubtless, accom- 

 plishes the same effect in leaves of Elm, Buttonwood, 

 Beech and many more. 



The red colors now remain for consideration. I\Iicro- 

 scopic examination of a thin cross-section of a red leaf 

 of Japanese Ampelopsis shows that while the bounding 

 wail of each leaf-cell is lined with colorless protoplasm 

 embedded with green chlorophyll granules, the interior of 

 each cell is occupied by a bright lake-red fluid. This cell- 

 sap, as it is called, is mostly water in which is dissolved 

 the red pigment, erythrophyll, if we may add one more 

 technical term. We may obtain this pigment from Ampelop- 

 sis, Maple, Huckleberry and other leaves vi'hich turn red by 

 boiling them in water, which dissolves out the erythrophyll, 

 rendered impure, however, by more or less of the gold- 

 yellow pigment already referred to. Evaporating the solu- 

 tion gives a red gum-like solid which is found in many of 

 the so-called evergreen leaves that are red. Winter leaves 

 of Cranberry soon lose their water by evaporation and pre- 

 cipitate in each cell a solid mass consisting almost wholly 

 of tannin, either colorless, yellow or colored red by ery- 

 throphyll. Tannic acid accumulates in leaves, especially 



