THE FLOWER. 



43 



175. Transformation of stamens iu roses. 



17(i. Hooded Columbine, 

 showing one series of 

 aatbei's transformed and 

 connected together. 



delicate, and their colour more brilliant, but their claw, Umb, and nerves, and their 

 usually flat shape, all reveal their foliar nature. 



The third whorl, or andrcecium, bears much analogy to the second ; the relative 

 position of the stamens and petals is always the same, and these sometimes present 

 an insensible transition from one to the other; as in semi-double flowers, where some 

 of the stamens are changed into petals ; in partially double flowers, where all the 

 stamens are so changed; and in full double flowers, where the carpels also have 

 become petaloid {Ranunculus, Columbine, Rose) . In Rosa centifolia (fig. I 75) , par- 



6 ticularly, the successive steps 

 by which a stamen becomes a 

 petal are obvious ; sometimes 

 the anther enlarges, and one 

 cell reddens (6) ; or both cells 

 lengthen (5) ; or the connective 

 reddens and dilates, and bears on one side a yellow scale, which 

 recalls an anther- cell (4, 3) ; offcenest the stamen expands at once 

 into a complete petal (2) ; sometimes (1) the proximity of the 

 calyx seems to influence this petal ; a green midrib traverses its 

 coloured blade, and it becomes sepaline in the middle, petaline on the sides. In the 

 double Columbine (fig. 176), the anther swells, and forms a hooded petal; and some- 

 times, but more seldom, the filament dilates into a flat petal. 



The fourth whorl or pistil is the central; its position and the pressure of 

 the surrounding organs influence its form in many ways, and hence disguise its 

 origin ; but when the carpellary leaves are free {Columbine, fig. 12), or solitary {Pea, 

 fig. 14), their foliaceous nature is obvious, and especially in anomalous cases, as 

 the following. 



Anomalies. — In the Columbine (fig. 177) the five carpellary leaves (f.c) instead 



of being folded to form a protecting cavity for the 

 S I young seed, have been found to remain flat, and 

 bear along their edges (or placentas) small leaf-buds 

 (p.o) ; these buds, which nor- ^ 



mally would have contained 

 an embryo, were mostly open ; 

 some few, though empty, 

 were curved, and suggestive of 

 their normal function; fertili- 

 zation had not taken place, 

 N, P, c,aud the unfertilized stigma 

 was reduced to a small glan- 

 dular head (St), terminating 

 the midrib of the carpellary 

 leaf. In the double Cherry (fig. 178), the free edges of the two carpels (p.c) bear 

 no buds, and their blade or ovary, which altogether resembles an ordinary leaf, 

 folded along its paidrib (N.m), is lengthened into a style-like-^eck, terminated by 

 a spongy tubercle representing the stigma. 



....F.o 



177. Monstrous Columbine. 



178. Double Cherry. 

 Flower out virtically ; s, sepals; 

 p, petals ; F.c, carpellary leaves ; 

 K.m, median nerve or style. 



