ORGANS OP FRUCTIFICATION. 



67 



in!?, as it does in the original, a crown or 

 cbuplct. 



Tlie corolla is monopetaloits, or formed of one 

 piece, as in the fox-glove, 

 bind-weed, and deadly 

 night-shade; or polypetal- 

 ous, composed of several 

 petals, as in cut 40, d, d, 

 and in the rose, pink, wall- 

 flower, and many others. 

 The corolla is divided into 

 the tube, the mouth, and 

 the border ; the petals into 

 the claw and lamina, or 

 border; the figures and 

 numbers of the petals vary in different species. 

 The calyx is regular when its incisions and 

 divisions are equal to each other, and symmetri- 

 cally placed; and irregular when its incisions 

 are unequal, and its parts do not correspond, 

 such is the snap dragon, hooded mill foil, &c. 



The monopetalous corolla assumes various 

 forms, such as the tubular, campanulate, urceol- 

 ate, or pitcher shaped, salver shaped, stellar. 



The irregular monopetalous corolla is said to 

 be two lipped, or labiate when separated into an 



41. 



a. 6. Om dt 



upper and under lip, as in thyme, balm, rose- 

 mary, fig. a, h; it is personate, or masked, when 

 divided into two unequal lips, resembling some- 

 what the mouth of an animal, fig. c; urceolate 

 or pitcher shaped, as in the heaths, fig. d. The 

 polypetalous corolla may consist of two parts, as 

 in enchanters, night-shade ; or of three, four, 

 five, or six petals. 



The papilionaceous corolla '-- 



is exhibited in the common 

 pea, iig 42, when the petals 

 are irregular, and so placed as 

 to resemble the wings of a 

 butterfly. 



The petals may be opposite 

 to the divisions of the calyx, 

 and thus correspond with 

 their surfaces, or they may 

 alternate with these, and cor- 

 respond to the divisions of the calyx. 



The colour of the corolla is either a pure and 

 beautiful white, as in the guelder rose and 

 magnolia; or various shades of red, as in roses; 

 or yellow, blue, violet purple, and other inter- 

 mediate shad-s. Its use is evidently along with 



, calyx; A, oori)IIa. 



rt, ovary; fi.style; r.stljf- 

 nia; (/, filament; c,e, an- 

 thers. 



the calj'X to protect the sexual organs, and en- 

 sure the deposition of the pollen on the pistil, 

 and in most plants it disappears immediately 

 after this office is performed. Yet, the corolla 

 is by no means essential to the structure of a 

 fruitful plant, as many classes are entirely desti- 

 tute of such an appendage. 



The annexed cut exhibits 

 the usual manner in which 

 the sexual organs are con- 

 tained within the corolla. 



The stamen answers the 

 same purposes in planta as 

 the male organs in animals ; 

 in other words, it contains 

 the substance by which the 

 fecundation of the germs is 

 effected. It is generally 

 composed of three parts: 

 1. The anther, a kind of 

 membranous bag, having a 

 double internal cavity, formed of two cells in con- 

 tact with each other ; 2. The pollen, a substance 

 commonly formed of small vesicular grains, 

 which contain the parts necessary for fecunda- 

 tion ; 3. The filament, a thread-like appendage 

 by which the anther is frequently supported. 

 Such ai'e the three parts of which the stamen is 

 usually composed. But of these parts two only 

 are essential to it, the anther and the pollen. 

 The filament is merely an accessory part of the 

 stamen, and is accordingly often wanting, the 

 anther being then directly attached to the body 

 on which it is inserted, without the intervention 

 of a filament. In this case the stamen is said 

 to be sessile. 



The essence and perfection of the stamen, con- 

 sists in the presence of the anther. But in order 

 that this organ may be fitted for performing the 

 functions allotted to it by nature, it must not 

 only contain pollen, but must also open, that the 

 pollen may come into contact with the stigma j 

 otherwise fecundation could not take place. ' 



The number of stamens vary in the different 

 families of plants. Some flowers have only one 

 stamen, as the Mppuris or mares-tail; others have 

 two, as veronica; others three, as the grasses, and 

 so on, till we come to an indeterminate number. 

 The firat classes of the Linnean system are de- 

 termined by the number of stamens, the terms of 

 which will be explained in the table to be after- 

 wards given. The manner in which the stamens 

 are inserted, afford also distinctive characters. 

 Thus, if they are inserted in the receptacle, as 

 in ranunculus, they are said to be liypogynoxis ; 

 if in the corolla, as in veronica, they are epipe- 

 ialous; if in the calyx, as in the family cpilo- 

 bium, they are periffj/noiis; and if in the ovary, 

 as in the orchis family, they are called epigz/nmis. 

 The relative proportions of the stamens to one 

 another, and to the several parts of the flower. 



