of many other varieties of fruit and flowers. The Christmas- 
flowering and picotee types of sweet pea are other examples. 
The former is claimed by its originator to be a cross between the 
true sweet pea and a variety of vetch; while the first variety of the 
latter type won an award from the Royal Horticultural Society of 
England under the name of “Blue Hybrid”, the belief being that 
it was a cross between the true sweet pea, Lathyrus odoratus, and 
the blue-flowered Lathyrus Magella?iicus , the Lord Anson’s pea of 
the old-fashioned gardens of our grandparents. In another 
Leaflet I hope to show why it is important that we should dis- 
cover all we can about the laws of heredity as soon as possible; 
why, in the end, that we shall find the so-called impractical scien- 
tific method to be in reality the most practical of methods. 
For those of you interested in making of hybridizing plants 
a pastime, and having neither the patience nor desire to do scien- 
tific work, I would say, by all means cross the plants you care 
most about and see what you can get. I am certain there is a 
rich field of exploration before you, and one in which, if pursued 
for any length of time, you will find absorbing interest, even 
though you are not able to give to the gladioli the perfume of a 
sweet pea, or to make a rose that is a pure blue and immune to all 
diseases. But there is one caution I almost forgot to mention 
regarding the kinds of plants that may be successfully crossed. 
Unfortunately, or fortunately, depending on whether you are a 
plant breeder or a plant classifier, egg plants apparently will not 
cross with willows, or oak trees with sweet peas. In general, 
plants that are most closely “related” will cross most easily. 
For example, varieties of the same species are more certain to 
cross successfully nine times out of ten than two varieties of dif- 
ferent species that belong to the same genus. And again, species 
belonging to the same genus may be expected when crossed to 
produce seed more often than crossings of plants of two species 
from separate genera, though belonging to the same family. 
Thus, varieties of pansy cross easily among themselves. The 
same is true of beans, corn and peas. Among the forty or more 
species of the genus Nicotiana (the genus of which our tobacco is 
a member) some species, such as the little red-flowered N. forget- 
iana and the large white-flowered N. alata, are easily crossed, 
while between other species, such as N. plumbaginifolia and N . 
tabacwn , a successful cross has never been made, though often 
tried. All our varieties of petunias are said to have come from 
crossing the two species, Petunia violacea and Petunia ?iyclagy?ii- 
flora. The species of the genus Viola , to which our pansies and 
violets belong, cross easily among themselves even under wild 
conditions, and this is true of the species of many other well- 
known genera, such as Pubus (raspberries and blackberries), 
