THE FLOBAL ENVELOPES. 



69 



379. When the floral members are arranged in an 

 exact circle, neither being higher nor lower than its fel- 

 lows, their edges will be applied to each other without 

 overlapping, as in the Hydrangea and Linden. The 

 form of this mode is shown in the diagram, fig. 5, and is 

 called Valvular. 



380. In the Poppy the corolla is crumpled together; 

 and there are some other, but not important varieties. 



THE CALYX. 



381. When both whorls of the floral envelopes are pre- 

 sent, the outermost is called the Calyx. This name 

 literally means cup, and refers to the cup-like cavity in 

 which it holds the other parts of the flower, as in figs. 7, 

 8 and 9. The sepals, or leaves of the calyx, generally 

 exhibit the green color, and coarser texture, of ordinary 

 leaves ; but sometimes they are endowed with the bril- 

 liant hues, and more delicate organization, which have 

 been supposed to belong exclusively to the corolla. 



382. Elementaky Composition. — The anatomical 

 structure of the proper calyx is identical with that of the 

 ordinary leaf, the pulpy expansion being composed of 

 parenchyma, and the framework of woody or fibrous 

 tissue, but when it is colored, chromule (66) is developed 

 instead of chlorophylle, and the whole texture is finer and 

 more delicate. The sepals are sometimes distinct ; but 

 they more frequently cohere by their edges, as in the 

 Eose, when the calyx is called Monosepalous ; yet 

 strictly speaking, no calyx can be said to be composed of 

 a single leaf. 



383. A very important generic distinction is drawn 

 from the position of the calyx in regard to the Ovary, 

 or hollow part of the base of the pistil, containing the 

 Ovules, or eggs of the plant, which are the rudiments of 

 the seed. The calyx is 



(1) Inferior, when it is free, or distinct from the 

 ovary, as in the Tobacco and Campion, figs. 7 and 8, and 

 also in fig. 16; and 



(2) Superior, when it adheres to the ovary, as in the 

 Bell-flower, fig. 9. Thus when the calyx is inferior, the 

 ovary is superior ; and the reverse. 



384. Sometimes the sepals are in two circles, or 

 whorls, as in the Strawberry, fig. 19. The outer and 

 smaller divisions of such a calyx are called Beaoteolbs. 



385. The dry and membranaceous envelopes which 

 inclose the spikelets of flowers in Grrasses are called 



Glumes ; and they correspond with the Involucre. 

 Those which immediately inclose the single flower, are 

 termed palese, the parts or pieces of which, usually two, 

 are Valves. At flg. 14 is a spikelet of the Oat with its 

 glume, g1, its paleae, ^e, which correspond with the floral 

 envelopes, calyx or corolla, and an abortive flower at /s. 

 The largest palea has a stout awn, a, 



386. Sometimes the calyx is reduced to a cluster of 

 hairs surrounding the florets of a compound flower, as 

 may be seen in the common Groundsel, flg. 11, which is 

 invested by its hairy envelope, called the Pappus. At 

 fig. 6 is the pappus of the Dandelion, which is borne on a 

 stalk, or sti-ge. There are several forms of pappus which 

 afford specific distinctions in this large and difficult 

 Order. They are 



(1) Pilose, composed of simple hairs; 



(2) Plumose, when each hair is feathered, or fringed 

 with smaller hairs ; 



(3) Setose, when the hairs are stiff or bristly ; and 



(4) Paleaceous, when dilated so as to become chaffy. 



387. When the outer envelope incloses many flowers, 

 it is called an Involucre. Sometimes the involucre is 

 composed of green leaves, and resemble a calyx, as iu the 

 Marigold, fig. 12, and the Fennel, fig. 15, as well as in 

 all the two great Orders which those plants represent ; 

 at others it is brilliant, delicate, and petal-like, as in the 

 Low Cornel, fig. 17. The Spathb, as seen in the Ameri- 

 can Calla, fig. 10, is a kind of involucre. Sometimes the 

 spathe is exquisitely delicate ; and it always constitutes 

 the chief beauty of the flower. In the Fennel tribe, fig. 

 15, the division which incloses an umbellet, or partial 

 umbel, is called an Involucel, while the bracts which 

 are situated at the hase of the compound umbel, and in- 

 close the whole inflorescence, are called the General 

 Involucre. In the Wall-flower, flg. 18, and other plants 

 of its family, the calyx is swelled out at base, and is said 

 to be gibbous. 



THE corolla. 



388. Elementary Composition. — As the two sets 

 of floral envelopes are at times indistinguishable, there 

 can be no absolute difference of anatomical structure, 

 only that a superior degree of fineness and delicacy is 

 found chiefly in that form which is, by contrast with the 

 coarser and outer whorl, termed the Corolla. 



389. The parts of the corolla, like those of the calyx, 

 are sometimes confluent. When this happens the flower 



Define the name. Divisions of the Calyx. When the sepals cohere what is 

 It? Is the term proper ? What important generic distinctions? Define each 

 position. When the Ovary is below how is the Calyx — how in the reverse ? Is 

 the Inferior Calyx free or adherent to the Ovary ? The Superior ? When the 

 eepab aie in two whorls, what are the smaller? DefineOvary — Ovules. Calyx of 



Grasses. Describe. With what do the outer envelopes correspond— the inner ? 

 Name of the first — of the second. How many parts usually— what termed ? In- 

 stance. How is the Calyx in the Compositae — its name — stalk of the pappus? 

 Forms of pappus. Define each. Elementary composition of the next whorl. Its 

 name. What are tho divisions called? When they are confluent how is the corolla? 



