THE FLOKAL ENVELOPES. 



73 



single rosaceous petal. The symmetry of both these 

 flowers is destroyed by Suppression. 



406. The Nectary. — There are several irregular 

 forms of the corolla, to which the old Botanists gave the 

 name of Nectaries, or organs for secreting honey. 

 These are of many different forms, as the inflated, or 

 hooded petal of the Lady's-Slipper, the spurs of the 

 Columbine, Nasturtion, and Violet, and the transformed 

 stamens in Parnassia and the petals of the Passion-flower. 

 These are all kindred processes, now being considered as 

 peculiar, or abnormal conditions of the petals ; and the 

 Nectary, as a distinct organ, is not admitted into the 

 nomenclature of modern science. 



407. The heads in the Order Composita; are marked 

 by three principal distinctions, which are of high import- 

 ance in determining the genera. The small flowers that 

 make up the heads are called Florets. The heads are 



(1) Discoid, when the florets are all tubular, as in 

 the Burdock and the Thistle, fig. 2 ; 



(2) Radiant, when the florets are all flat, or strap- 

 shaped, usually called Lighlate, as in the Dandelion, 

 fig. 3 ; and 



(3) Radiate, when the central, or disk florets, are 

 TUBULAR, and the border, or ray florets ligulate, as in 

 the Marigold, fig. 7, and the Aster, fig. 6, where the tu- 

 bular and ligulate florets of the disc and ray, are seen at 

 the left and right. 



COLORS OF FLOWERS. 



408. Pliny long ago called " blossoms the joy of 

 TREES ;" and fanciful as the thought is, we feel, even to 

 this day, that there is not less of truth than poetry in the 

 sentiment ; for flowers, more than most other things, 

 minister to that love of beauty, which is one of our in- 

 most affections. While the foliage of trees and plants 

 exhibits that hue which is most grateful and soothing to 

 the eye, the richest tints, and the most splendid combi- 

 nations of color, are reserved for flowers. We repose 

 amid the embowering greenness of woods, or the waving 

 verdure of meadows ; but the sight of flowers stimulates 

 the mental affections, and we become excited by a finer 

 and more exquisite sense of beauty. 



409. Changes of Color. — Transient as they are, 

 the tints of flowers often undergo several changes during 

 their short life. In the small Forget-me-not, the petals 

 are of a delicate rose-color when they expand, but turn 

 to a bright blue as they mature. Eed, purple, and blue 



What arc Nectaries— what now considered ? Distinction of heads in the 

 Compositfe. Name of flieir small flowers. Deiane each form. How are the 

 florets when the head is Discoid— Radiate— Eadiant ? Words of Pliny. Why 

 true now? How does the sight of green foliage aflfect us — flowers? Changes 



10 



flowers sometimes become white ; and yellow, under the 

 infiuence of light, occasionally assumes the same color. 

 But the most remarkable instance of these changes is 

 that familiar one furnished by the Hydrangea, whose 

 flowers are pea-green when they first open, and afterwards 

 appear in several different colors, and different shades of 

 the same color — white, yellow, pink and purple. 



410. Odor of Flowers. — This, as has already been 

 shown (60), is owing to the presence of a volatile oil. 

 The perfume of flowers is excited by moisture, and hence 

 they give out their fragrance most freely in the evening, 

 when the air is laden with dew. This is particularly 

 true of that class which Linnseus poetically denom- 

 inated " Melancholy Flowers." These are characterized, 

 not only by their delicious fragrance, but by their brown- 

 ish, greenish, and yellowish hues, such as the Wallflower 

 and the Evening Primrose. White flowers are generally 

 fragrant, and there is found to be considerable analogy 

 between the color and odor of flowers generally ; those 

 of certain colors agreeing remarkably in the peculiar 

 character of their perfume. 



411. Duration of the Floral Envelopes. — This 

 quality is subject to great variations. The sepals, or 

 petals, are — 



(1) Caducous, when they fall soon after the expan- 

 sion of the flower, as in the Rock-Rose ; or when they 

 drop before the flower is completely open, as in the calyx 

 of the Poppy, and the corolla of the Grape ; 



(2) Deciduous, when they fall before the perfection 

 of the fruit, as is the most common case ; and 



(3) Persistent, when they remain after the fruit is 

 matured, as in the Calyx of the Apple and Strawberry. 



412. Functions op the Floral Envelopes. — The 

 ofl&ce of the Calyx and Corolla, as sheltering and protect- 

 ing organs, must be obvious even to the most superficial 

 observer, since they not only often close spontaneously 

 in bad weather, but many species habitually enfold the 

 tender organs they surround, not only at night, but to 

 afford shelter from the sun. The flowers of the Dan- 

 delion, and others of the order Compositse, close in bad 

 weather, and expand in clear sunshine ; while those of 

 many other tribes have regular hours of closing and un- 

 folding. 



413. That the Corolla is acted on in a very peculiar 

 manner by light, is no longer a secret. It does not, like 

 the green parts, evolve oxygen, but abstracts it from the 

 air, giving off carbonic acid gas in its place. By this 



of color— describe. Remarkable instance. Flowers most fragrant at evening- 

 why? Of what class especially true ? Instances. Duration of Floral Enve- 

 lopes — distinctions— define. Most obvious Function of Floral Envelopes? 

 Give the facts. How affected by light? What chemical influence? 



