UNION OR COHESION OF THE STAMENS. 205 
pistil become completely united also, and thus form a column 
in the centre of the flower, as in the Orchis (fig. 546), and Birth- 
wort (fig. 547); this column is then termed the gynostemiwm, 
and the flowers are said to be qynandrous. 
3. Union or Cohesion.—When the stamens are perfectly free 
and separate from each other, as in the Vine (fig. 518), they are 
said to be free or distinct ; when united, as in the Mallow (jig. 
549), they are coherent or connate. 
When the stamens cohere, the union may take place either 
by their anthers, or by their filaments, or by both anthers and 
filaments. When the anthers unite, the stamens are termed 
syngenesious or synantherous (fig. 548). This union occurs in 
Brie. 548..= Fie. 549. Fie. 550. 
Kies 55. 
Fig. 548. Syngenesious anthers of a species of Thistle ( Carduus).— Fig. 549. 
Monadelphous stamens of a species of Mallow (Malva).— Fig. 550. Mona- 
delphous stamens of Wood Sorrel (Oxalis), forming a tube round the pistil. 
— Fig. 551. Male flower of Jatropha Curcas. ¢. Calyx. p. Corolla. e. 
Stamens united by their filaments into a tube, a, which occupies the centre 
of the flower, as there is no pistil. 
all the Composite, the Lobelia, and in some other plants. 
When the anthers thus unite the filaments are commonly, 
though not always, distinct. When union occurs between the 
stamens, however, it is more common to see the filaments 
united, and the anthers free. This union by the filaments may 
take place in one or more bundles, the number being indicated 
by a Greek numeral prefixed to the word adelphous, which 
signifies brotherhood. Thus, when all the filaments unite to- 
gether and form one bundle, as in the Mallow (jig. 549), and 
Wood Sorrel (fig. 550), the stamens are said to be monadelphous. 
When such a union takes place in a complete flower, the coherent 
filaments necessarily form a tube or ring round the pistil placed 
in their centre, as in the Wood Sorrel (fig. 550) ; but when the 
pistil is absent, and the flower therefore incomplete, the united 
filaments form a more or less central column, as in Jatropha 
Curcas (fig. 551, a). When the filaments unite so as to form 
