294, METAMORPHY. 
anther-lobes are usually atrophied, and little or no 
pollen is formed. 
An occurrence of this nature in Tacsonia pinnati- 
stipula, in conjunction with the partial detachment of 
the stamens from the gynophore, led Karsten to estab- 
lish a genus which he called Poggendorfia.* 
From the subjoined list of genera in which petalody 
of the stamens, in some form or other, has been 
observed, it will be seen that it happens more often 
in plants with numerous distinct organs (Polypetale, 
Polyandria, Polygynia, &c.) than in other plants 
with a smaller number of parts, and which are more 
or less adherent one to the other. ‘The tendency to 
petalification is, moreover, greater among those plants 
which have their floral elements arranged in spiral series, 
than among those where the verticillate arrangement 
exists; and in any given flower, if the stamens are 
spirallyarranged while the carpels are grouped in whorls, 
the former will be more liable to petalody than the 
latter, and vice versd. It has been before remarked, 
that this condition is far more common in plants whose 
petals, &c., have straight veins, lke those in_ the 
sheath of a leaf, than in those the venation of which 
is reticulate, as in the blade of the leaf. It must also 
be remembered that in the same genus, even in the 
same species, different kinds of doubling occur. 
Familiar illustrations of this are afforded in the case 
of anemones, columbines, fuchsias, and other plants. 
The existence of ‘‘ compound stamens” in some 
flowers, as pointed out by Payer, and others, and the 
researches of Dr. Alexander Dickson, confer additional 
importance on the subject of petalody, and necessitate 
the examination of double flowers with special reference 
to these compound stamens, and to the order of their 
development.’ The presence of these compound sta- 
1 Karsten, ‘ Flor. Columb. Spec.,’ tab. xxix. 
2 See Dickson, “ On Diplostemonous Flowers,” ‘Trans. Bot. Soc. 
Edin.,’ vol. viii, p. 100; and on the Andrecium of Menizelia, &c., in 
Seemann’s ‘ Journal of Botany,’ vol. iii, p. 209, and vol. iv (1866), p. 273 
(Potentilla, &c.). 
