A ete ey A Oe hy a 6 4 L : 
is 2 rh ‘ 
ay 
‘ ‘ pa at SY Oe PON i ut ; 
=f Ve ; . J 
ess S45 beens | - a oo t ’ . v = 
; ‘ : wa s , 
r a . . : 
eae jah 
Reece ae moe The Life of the Plant. — Mie is Ve eee 
sepals into bracts or foliage-leaves is still more frequent, a 
common and beautiful example of which occurs in the calyx 
of the rose. One of the best known instances of metamor- 
phosis of the reproductive organs into perianth-leaves is fur- 
nished in the case of the common garden tulip, in which the 
three carpels and the six stamens are all transformed into 
ordinary petals ; [and the same is the case with the greater 
number of double flowers, as the rose, camellia, pink, &c. ]. 
That these leaves are actually lower stages of development 
of the organs, is shown very clearly in an imperfectly double 
tulip, in which some of the leaves are divided through their 
mid-rib into two altogether unlike halves, a halfstamen and 
a half-petal. These imperfect transformations are also fre- 
quently seen in the peony and the water-lihes (Nympheze- 
aceze)—|in the case of the white water-hly, Vymphea alba, 
even in the wild state|—these instances affording convincing 
proof that the ‘doubling’ of flowers is due to retrogressive 
metamorphosis. It has already been mentioned that this -— 
metamorphosis 1s very commonly accompanied by an in- 
crease in the number of parts of the flower ; and it is not 
surprising that such retrogressions should also be associated 
with abortion. Perfectly double flowers are of course 
sterile ; but even when the metamorphosis affects the sta- 
mens only, the pistil is in that case also always less perfectly 
developed, and less or even not at all capable of being © 
fertilised by pollen from other flowers. In many cases 
the doubling is only apparent, as in the cultivated’ Com- 
positze, such as the aster and dahlia, in which the altered 
appearance is produced by the transformation of the yellow 
tubular flowers of the disc into ligulate flowers of a different 
colour ; but sometimes only by the increase in size and 
change in colour of the tubular flowers. Jn this case also 
the transformation is usually associated with sterility. 
When the retrogressive metamorphosis goes back still 
further than in the doubling of flowers, the brightly coloured | 
petals lose their colour, and the flower becomes green. 
