50 ^YsrEMATIC P()M()JJ)(iY 



hybrids of wliidi there are many examples among fruits; when 

 between speeies of ditt'erent genera, genus- or higcncrw-hyhrida 

 of wliieh the only one among hardy fruits is between the pear 

 and the {juinee. There are no means of determining beforehand 

 whether any two varieties, species, or genera will eross-fe?'tilize. 

 More and mo -e, hiihrid is used to designate all crosses. 



Crosses and hybrids may be affected profoundly when they 

 arise from forms noticeably different, and in either classifying 

 or describing fruits it is desirable to know whether the plant 

 has come from self-fertilization, as a cross, or as a hybrid. 

 Plants arising from selfing usually lack vigor ; crosses, as a rule, 

 are as vigorous as the parents, or more so ; while hybrids, 

 especially among the fruits w^ith which this text is concerned, 

 are more vigorous in growth, more luxuriant in foliage, and often 

 more fruitful than either parent. Some hybrids, however, are 

 less fertile than their parents and some will not bear fruits or 

 seeds; the latter is the case with hybrids betw^een several species 

 of brambles and between the gooseberry and black currant. The 

 reproductive organs are often wholly or in part malformed or 

 missing and ovules and pollen-grains imperfect. Very often the 

 seeds seem to be perfect, as in the pits of hybrid cherries, but 

 may not germinate. Malformation of any part of a hybrid is 

 common. Most fruits are crosses, but many are hybrids, so that 

 the manner of origin must be studied as a possible cause of 

 striking characteristics. 



82. Scent in flov^ers. — Attention has been called to the variety 

 of vivid colors in the corollas of flowers of many fruits. These 

 colors serve to attract insect visitors whereby proper pollination 

 is secured. When size and color of corolla are lacking, as in 

 grapes, gooseberries, and currants, and very often associated 

 with a showy corolla, scent is a potent means of attracting in- 

 sects. Indeed, flowers of each species of hardy fruits have a 

 characteristic odor and many varieties, especially of plums, 

 cherries, and grapes may be told by this odor. Insects visit 

 flowers for nectar, and color and scent serve as guides. Nectar 

 is secreted by glands called nectaries. Although usually too 

 small to be readily seen with the unaided eye, they are sometimes 

 verv characteristic. 



