568 THE GENESIS OF NEW FORMS AS A RESULT OF CROSSING. 



is the stock from which the garden Auriculas are derived. The colour of the corolla 

 in P. Auricula is a uniform golden-yellow excepting that at the throat, i.e. at the 

 junction of the tube with the expanded limb, there is a floury efflorescence which, 

 like that covering the calyx, pedicels, and bracts, is due to a peculiar modification of 

 the epidermis. The corolla of P. hirsuta is bi-coloured; the segments of the limb 

 are violet-red, whilst the throat is white. The two tints are sharply marked off 

 from one another, and in consequence a white five-rayed star is seen in the middle 

 of the flower. There is in this case no trace of a floury efflorescence. In the 

 hybrid offspring of these two Primulas both the violet-red of the limb and the 

 white of the throat are blended with yellow; the former exhibits a touch of brown, 

 and in the middle of the flower is a pale-yellow star. 



It is much less common for those floral colours which are inherited by a hybrid 

 from the parent-species to be displayed in juxtaposition than in a blended condition. 

 Since the time of the Roman Empire gardeners have crossed the red-flowered Rosa 

 Gallica and P. Da7)iascena with the white-flowered Rosa alba and obtained thereby 

 hybrids in which the petals are striped and spotted longitudinally with red and 

 white (so-called " York and Lancaster " roses). Similar cases occur amongst hybrid 

 Calceolarias, Pinks, Petunias, and Wood-Sorrels, and instances of Tulip and Iris 

 hybrids are also known wehere the perianths exhibit the two diflferent colours of the 

 parent-species side by side in streaks and patches. A hybrid of Iris Florentina and 

 /. Kochii is especially deserving of notice. The perianth in /. Florentina is milk- 

 white and that of I. Kochii is dark violet. The hybrid of these two species was 

 first obtained in May, 1871, in the Botanic Garden at Innsbruck; one of the indivi- 

 dual plants thus produced had two of the outer and one of the inner members of the 

 perianth shaped like those of I. Kochii and of a deep violet colour, and one of the 

 outer and two of the inner members shaped like those of 1. Florentina and milky- 

 white in colour. This arrangement of colours re-ajjpeared year after year until in 

 1877 a single flower, in which the lower white members had some dark violet 

 streaks widening out from the middle to the edge of the perianth also made its 

 appearance. A second plant of the same hybrid developed flowers which only 

 differed from those of /. Florentina in that a few of the white petals had dark 

 violet streaks widening out towards the circumference. An equally noteworthy 

 case is that of a hybrid reared in the Botanic Garden at Florence from /. Ger- 

 manica and I. sainhucina, of which a specimen was sent to me in 1872. One 

 inferior and two superior perianth-members displayed on one half of their surfaces 

 the colour and pattern peculiar to /. samhucina, and on the other half those charac- 

 teristic of /. Germanica. The rest of the perianth could not be distinguished 

 except by its smaller size from that of Iris Germanica. 



It must not be supposed, however, that the presence of variegated stripes, 

 patches, or speckles on petals is always an indication of hybridity. Viola poly- 

 chroma, a very common Alpine species, not infrequently produces simultaneously 

 two, three, or four open flowers, every one of which presents a different mixture of 

 tints, and amongst plants of this species covering only a small patch of ground it 



