OUTLINES OF BOTANY. 



direction in the other whorls does not prevent the flower being classed as 

 Tegular, if the corolla or perianth is conspicuous and regular. 



9. The Calyx and Corolla, or Perianth. 



96. The Calyx (90) is usually green, and smaller than the corolla; 

 sometimes very minute, rudimentary, or wanting, sometimes very indis- 

 tinctly whorled, or not whorled at all, or in two whorls, or composed of a 

 large number of sepals, of which the outer ones pass gradually into bracts, 

 and the inner ones into petals. 



97. The Corolla (90) is usually coloured, and of a more delicate tex- 

 ture than the calyx, and in popular language is often more specially meant 

 by the flower. Its petals are more rarely in two whorls, or indefinite in 

 number, and the whorl more rarely broken than in the case of the calyx, at 

 least when the plant is in a natural state. Double flowers are in most cases 

 an accidental deformity or monster in which the ordinary number of petals 

 is multiplied by the conversion of stamens, sepals, or even carpels, into 

 petals, by the division of ordinary petals, or simply by the addition of super- 

 numerary ones. Petals are also sometimes very small, rudimentary, or en- 

 tirely deficient. 



98. In very many cases, a so-called simple perianth (15) (of which the 

 parts are usually called leaves or segments) is one in which the sepals and 

 petals are similar in form and texture, and present apparently a single 

 whorl. But if examined in the young bud, one half of the parts will gene- 

 rally be found to be placed outside the other half, and there will frequently 

 be some slight difference in texture, size, and colour, indicating to the close 

 observer the presence of both calyx and corolla. Hence much discrepancy 

 in descriptive works. Where one botanist describes a simple perianth of 

 six segments, another will speak of a double perianth of three sepals and 

 three petals. 



99. The following terms and prefixes, expressive of the modifications of 

 form and arrangement of the corolla and its petals, are equally applicable 

 to the calyx and its sepals, and to the simple perianth and its segments. 



100. The Corolla is said to be monopetalous when the petals are united, 

 either entirely or at the base only, into a cup, tube, or ring; polypetalous 

 when they are all free from the base. These expressions, established by a 

 long usage, are not strictly correct, for monopetalous (consisting of a single 

 petal) should apply rather to a corolla really reduced to a single petal, 

 which would then be on one side of the axis ; and polypetalous is some- 

 times used more appropriately for a corolla with an indefinite number of 

 petals. Some modern botanists have, therefore, proposed the term gamo- 

 petalous for the corolla with united petals, and dialypetalous for that with 

 free petals ; but the old-established expressions are still the most generally 

 used. 



101. When the petals are partially united, the lower entire portion of 

 the corolla is called the tube, whatever be its shape, and the free portions of 

 the petals are called the teeth, lobes, or segments (39), according as they are 

 short or long in proportion to the whole length of the corolla. When the 

 tube is excessively short, the petals appear at first sight free, but their slight 

 union at the base must be carefully attended to, being of importance in 

 classification. 



102. The ^Estivation of a corolla is the arrangement of the petals, or 

 of such portion of them as is free, in the unexpanded bud. It it 



