THE ELOKAL ENVELOPES. 



67 



places on the receptacle, the calyx is below, or outside of 

 the corolla, the corolla of the stamens, and the stamens 

 of the pistils. The floral organs are then said to be 

 FREE, in opposition to that state where their insertion is 

 obscured by the adhesion of two or more whorls. 



364. Chokisis is an irregular multiplication produced 

 by a division of parts, as in the order Cruciferse, where 

 each of the external pair of stamens is supposed to be 

 formed by the division of one. 



365. Eegular Multiplication is the production of 

 two or more whorls in the place of one, as in the Pond- 

 LUy and Magnolia tribe, where the petals are thus mul- 

 tiplied, and in the Rose and Crow-foot tribes, where the 

 stamens and pistils occupy several whorls. 



366. iRREGHLAniTY OF FoKM occurs when the parts 

 of the same whorl are unequally developed, as in the 

 corolla of the Violet and the Pea, and the stamens of the 

 Cress tribe. If the perianth is regular, the stamens are 

 generally regular and symmetrical ; but they have a 

 strong determination to be unsymmetrical when the floral 

 envelopes are so. 



367. When both whorls are present, the floral enve- 

 lopes almost always, and the stamens generally, preserve 

 their true numerical relations; but proceeding inward, 

 the floral whorls have less and less room for expansion, 

 until in the pistils, or central whorl, the base often be- 

 comes contracted to a mere point ; and thus the several 

 members are either fairly crowded out of place, or the 

 adjacent parts coalesce, and form a single, or perhaps a 

 double organ, in the place of several. 



368. A flower whose parts are in twos, or multiples 

 of two, is called Dimerous, threes, Tkimbeous, fours, 

 Tetramekous, and fives, Pentamebous. The first num- 

 ber is rare. Monocotyledonous fiowers are almost al- 

 ways trimerous ; and a large proportion of the Dicoty- 

 ledonous are pentamerous. The whorls of the latter are 

 less frequently in fours, and seldom in twos. As a gene- 

 ral thing the number three marks the divisions of the 

 first, and five and four of the last. 



369. A Symmetrical Flower is one whose whorls 

 correspond in regard to numier. 



370. A Regular Flower is one whose parts corre- 

 spond in sise and form. 



371. A Complete Flower consists of the Essential 

 Organs and their two regular whorls of Envelopes. 



Which whorls usually preserve their symmetry ? In what direction does 

 symmetry decline? Why? What is a flower in twos— ia threes — in fours — 

 Infives? Which of these is rare? Which most common? Which distinguish 

 Endogens — Exogens. Define a Symmetrical Flower— Eegular — Irregular— Bar- 

 ren — Fertile— Perfect How when Polygamous ? 



372. An Infertile or Barren Flower is one that 

 contains only stamens, 



373. A Fertile Flower is one that contains only 

 pistils. 



374. A Perfect Flower is one that contains hath 

 stam,ens and pistils. 



375. The flowers are Polygamous when they consist 

 of Barren, Fertile, and Perfect flowers, mingled promis- 

 cuously. 



CHAPTER XXV. 



THE FLOKAL ENVELOPES. 



376. * Prefloeation is the manner in which a flower 

 lies folded in the bud. The same terms which are used 

 to express Prefoliation will, in a general sense, apply to 

 the structure of the flower-bud. The principal forms of 

 Prefloration are the Imbricate, the Convolute, and the 

 Valvular. 



377. When the floral leaves lap over each other in 

 the bud, like shingles on a house-roof, the prefloration is 

 said to be Imibricated ; and the same term is applied to 

 other parts. In the diagram, fig. 1. Plate XXII., this 

 form is shown, the divisions being arranged in a spiral 

 line from 1 to 5. This, however, is not the most com- 

 mon arrangement ; for when the parts are in fives, as in 

 the Rose and Apple, there will be two outer and two 

 inner, while the fifth division is exterior by one edge, 

 and interior at the other. Another form of the imbri- 

 cated prefloration is seen in flowers with four parts, 

 when the two opposite divisions will be external, as in 

 fig. 2. At fig. 3 the prefioration is such as occurs in 

 flowers like that of the Pea, and is called Vexillary ; 1 

 and 2 are the wings, or side petals, 4 the banner, or 

 large upper petal which becomes external, and 3 and 5 

 parts of the Iceel, or lower petal. 



378. The Convolute Prefloration appears to be 

 caused by the twisting of the several parts on their axis, 

 one edge being directed obliquely inward, while the other 

 overlaps its successor, as in the diagram, flg. 4. A va- 

 riety of this form occurs in Monopetalous corollas, as in 

 the Morning-Glory, which is not only twisted, but plaited 

 in the bud. Such prefloration is Supbrvolute. 



» ^Estivation is the term generally used to express the folding of the Flower 

 in its bud, and Yei-nation that of the Leaf; hut I prefer Prefloration and Prefo- 

 liation, as being truer to the facte, since Leaf-buds do not belong exclusively to 

 spring, nor Flower-buds to summer. 



General subject. Define the term. What synonyms generally used? 

 What corresponding terms may bo applied ? Three principal forms. Define 

 Imbricated — other forms. Name the outermost whorl of Envelopes. Define 

 the name. When but one whorl is present, what is it called ? 



