5 68 



Garden and Forest. 



[Number 197. 



Our Walnuts (Juglans) are notorious for the ease with which 

 they part with their foliage, while, on the other hand, their 

 allies, the Hickories (Hicoria or Carya), generally hold a con- 

 siderable quantity of their dead, dry and shriveled leaves with 

 a surprising tenacity through many hard frosts and high 

 winds. 



The Beech also holds its leaves later than the majority of 

 trees, and, apparently, there is not so much difference be- 

 tween the indigenous and the European species in their 

 period of falling, although the latter keeps a fresh appear- 

 ance for a longer time. Young Beeches are, apparently, 

 apt to retain their dry foliage longer than large trees ; but 

 any one who has walked through Beech woods in win- 

 ter cannot have failed to notice numerous cases of both 

 old and young trees retaining a considerable quantity of 

 leaves which had become so bleached that they were almost 

 of as pure a white color as the snow beneath them, 



Arnold Arboretum. J • G. J ack. 



The Colors of Flowers. — I. 



'"TO answer the question, " What is the primitive color of the 

 ■*- flowers, and what is the order of progression in ' color- 

 change,' if such there be?" it is not necessary to trace the 

 development of the flower back to primitive times, nor to 

 know whether it was a Buttercup which first unfolded its 

 petals to the sun, or whether it was a Dandelion or something 

 entirely different from either, for the same laws govern the 

 coloration of all flowers, whether they belong to the order 

 Ranunculaccce or not, and whether they are primitive or re- 

 cent ; neither is it important to know whether petals were 

 originally flattened and enlarged stamens or modified leaves. 

 Any one can easily solve the problem for himself by a study 

 of the native wild plants growing by the road-side or in the 

 fields and woods, and even if he should restrict his observa- 

 tion to a few acres about his summer residence in the country 

 that amount of territory would be ample. 



Mr. Grant Allen, in his admirable treatise on " The Colors of 

 Flowers," published in London in 1882, concludes that yellow 

 is the primitive color of flowers, and he also takes the ground 

 that petals are altered and modified stamens. He writes as 

 follows : " As the stamens of almost all flowers, certainly of 

 all the oldest and simplest, are yellow, it would seem natu- 

 rally to follow that the earliest petals would be yellow too." 

 Again: "All flowers, it would seem, were in their earliest 

 form yellow ; then some of them became white ; after that a 

 few of them grew to be red or purple ; and finally a compara- 

 tively small number acquired various shades of lilac, mauve, 

 violet or blue." " Petals are, in probability, originally enlarged 

 and flattened'stamens." 



This opinion is also held by others. The Rev. George 

 Henslow, in the " Origin of Floral Structures," writes : " Again, 

 when we come to Dicotyledons and find the prevailing tint of 

 stamens is the same (yellow) . . . we gather probabilities in 

 support of that view, etc. . . . but why the first color was yel- 

 low and why it ever gave place to red or blue is unknown." 



There are two.methods employed by Nature in the develop- 

 ment of colors : one may be called the imperfect or foliar de- 

 velopment, the other the normal floral process. In the first, 

 the colors, at least apparently, are evolved directly from the 

 green chlorophyl, as the reds, yellows and purples of autumn 

 leaves, for from some green-colored flowers a rather limited 

 number of dull reds, purples and yellows are produced. The 

 reds and reddish purples are, however, rare, and seen mostly 

 on the scales of involucres, where they are common, also on 

 the spathes of several of the Aracece, as Symplocarpus fcetidus 

 and Ariscema triphyllum (Jack-in-the-Pulpit), also in Salicornia 

 of our salt-marshes, which turns red in the fall, and in the 

 Castor-oil plant of gardens, which turns a reddish purple in 

 all its parts — leaves, stem and flowers. I do not find a satis- 

 factory example of yellow evolved directly from green among 

 our native plants. It is extremely doubtful if any pure yel- 

 low ever immediately succeeds green. This is somewhat 

 surprising when one considers the fact that yellow is one of 

 its component parts. There are, however, some greenish 

 yellow flowers, and these will be considered further on. 

 Among the green native flowers we find Smilax herbacea, S. 

 rotundifolia and S. glanca, central florets of Aster umbellaius, 

 Ampelopsis quinquefolia and variegated garden varieties, also 

 the garden Evonymus Seboldianus, and many smaller, low, 

 degraded plants. 



We will now turn our attention to the normal floral method 

 of the development of color, by which all the bright attractive 

 hues of the flowering world are produced, and first take up for 

 inspection Spiranthes gracilis, a pretty little plant of the Orchis 



family, with white flowers spirally disposed at the summit of 

 the scape. The lip is green, fringed around the edges with 

 white, and the other petals are wholly white. A small section 

 of the petals, placed under a magnifying-glass, appears to be 

 colorless and transparent, while the delicate net-work of the 

 tissue glistens like crystal ; yet this colorless tissue, in a mass, 

 reflects white. In the same manner a single leaf-like bract of 

 Monotropa uniflora, severed from the stem, appears colorless, 

 but two or more placed together, making a greater thickness, 

 reflect a decided white color. 



This feature should be especially noted for the reason that, 

 whenever the term colorless is used in this paper, it is not to 

 be taken in its literal sense, but is intended to signify a state of 

 incipient whiteness. Another point to be noted is, that the 

 white color directly succeeds the dark rich green of the lip. 

 In this one plant is found a clue to the solution of a problem 

 which has greatly perplexed botanists, namely, the problem of 

 the priority of color. In Spiranthes cernua green has disap- 

 peared, the corolla being entirely white. We will now endeavor 

 to demonstrate that the universal law of progression in color, as 

 regards the floral structure, is first from green to white ; or, 

 differently stated, Nature, before she begins to paint the more 

 refined and delicate tissue of the petals, by some secret 

 chemical process, completely eliminates the chlorophyl and 

 prepares a perfectly pure and white canvas upon which to 

 essay higher flights of fancy. 



The universality of the law that white directly follows green 

 may be demonstrated by the following illustrations, taken 

 from native plants in flower in August and September in 

 south-eastern Massachusetts, from which section also all other 

 illustrations are drawn, excepting an occasional garden-plant, 

 referred to on account of the facility in obtaining it for inspec- 

 tion. By confining our investigation in the mam to wild flow- 

 ers we avoid the complications arising from high cultivation, 

 hybridization, reversion, etc. One should bear in mind, in 

 this investigation, the well-recognized fact that the limb or 

 expanded portion of a petal, and especially the edges of the 

 same, usually are the first to assume the new color ; and that 

 where the change of color is not complete the base of the 

 flower, which is least exposed to the light, retains more or less 

 of the primary color. 



Examples : Nymphaa odorata. Sepals green outside, white 

 inside ; petals first partly green, followed directly by white. 



Mollngo verticillata. Petals green outside except the edges, 

 which are white ; white inside. 



Cornus florida. Corolla-like involucre changes from green 

 directly to a brilliant white. This is a large and beautiful 

 flower. 



Gnaphalinm polycephalum. Bases of the many white invo- 

 lucral scales green. 



Hydrangea paniculata. Gardens; marginal flowers green to 

 pure white. 



Spiranthes gracilis. Green to pure white. 



Bartonia tenella. Base of petal dark green to white. 



Daucus Carota. Flowers at first greenish, becoming white, 

 as also the upper half of all the pedicels. 



Erechtites hieracifolia. Flowers and tubefrequently remain- 

 ing green, but in many heads the minute corolla becomes pure 

 white, while the tube does not change color. 



Habenaria tridentata. Petals light green, becoming white. 



Cobea scandens. Gardens ; green, seemingly simultaneously 

 to white and purple. 



Plantago major and P. lanceolata. Green to colorless or 

 faint white. 



Cakile Americana. Calyx green, with colorless to white 

 edges, claws colorless or white, limb purple. 



Achillea millefolium. Tube and base green, limb white. 



Anthemis Cottila. Tube and base green, limb white. 



Rhus copalina. Usually green ; several shrubs, however, 

 were seen having a considerable number of white flowers, 

 which afterward turned red. 



Lilium super bum. Broad base of midribs green, surrounded 

 first by an area nearly white, succeeded upward by many 

 shades of yellow deepening to red. This is interesting in that 

 the whitish region lies between the green and yellow and does 

 not follow yellow. 



Heliotrope. Gardens; like preceding, the greenish centre is 

 followed by white, farther up by red or blue-purple. 



Chelone glabra. Green to white, the tip remaining slightly 

 green. 



Parnassia Caroliniana. White petals show the basal color 

 in the pretty green veining and green color on the outside of 

 the tip. 



Polygonum arifolium, P. Hydropiper acre, etc. Sepals green 

 to white. 



