356 SYMMETRY OF THE FLOWER.—UNION AND ADDITION. 
more of the floral circles ; or increase in the number of parts of 
a whorl. 
3rd. The suppression or abortion of one or more whorls ; or 
of one or more parts of a whorl. 
4th. Irregularity produced by unequal growth, or unequal 
degree of union of the members of the same whorl ; or by ab- 
normal development of the thalamus or axis of the flower. 
That part of Botany which has for its object the investigation 
of the various deviations from normal structure, both in the 
flower and other parts of the plant, is called Teratology. 
1. THE CHANGES DUE TO UNION OR ADHESION OF PARTS.—We 
arrange these in two divisions: one of which is characterised 
by the more or less complete union of the members of the same 
whorl ; and the other by the adhesion of the different whorls. 
The first is frequently termed coalescence, cohesion, or concrescence ; 
and the latter adnation or adhesion. 
a. Ooalescence, Cohesion, or Conerescence.—This is of very 
common occurrence in the members of the different whorls of the 
flower. Thus it occurs in the calyx, when it becomes monose- 
palous or gamosepalous; in the corolla, when it is monopetalous 
or gamopetalous ; in the filaments, when it gives rise to mona- 
delphous, diadelphous, and polyadelphous stamens ; in the anthers, 
when they are syngenesious or synantherous ; and in the pistil, 
when the carpels are syncarpous. 
b. Adnation or Adhesion of the different whorls is also by no 
means uncommon, ‘Thus the calyx may be united to the corolla, 
or to the andrcecium, or to both; or all these whorls may be 
united with the ovary. These different adhesions have been 
already explained, under the terms perigynous, epigynous (page 
254), as regards the stamens ; and superior (page 227) as applied 
to the calyx. Again, the stamens may be united to the corolla, 
when they are said to be epipetalous (page 253) ; or to the pistil, 
when the term gynandrous is used (page 255). All the changes 
due to union or adhesion of parts have been fully described in 
treating of the different whorls of the flower. 
2. ADDITION OR MULTIPLICATION OF Parts.—This may be also 
considered under two heads :—I1st. The addition of one or more 
entire whorls in one or more of the floral circles; and 2ndly, 
the increase in the number of the parts of the whorl, which is 
usually said to be due to the multiplication by division of 
any or all of the organs of a whorl. The former is commonly 
termed augmentation ; the latter chorisis, deduplication, or wi- 
linin). 
a Augmentation.—The increase in the number of whorls may 
occur in one or more of the floral circles. Thus the Barberry 
(fig. 789) has two whorls of sepals, two of petals, and two of 
stamens ; in this flower, therefore, we have an addition of one 
whorl of organs to each of the three external floral circles. In 
the Poppy, we have a number of additional whorls of stamens 
