THE PRODUCTION OF HORTICULTURAL VARIETIES. 



325 



increase in the number of the rays, there being a few more than could be 

 ascribed to ordinary fluctuating variability. From this small indication it 

 had to be worked up to the full display of all its potentialities. Finally, 

 it reached the type which is normal for other double composites, and since 

 that time it has remained constant. 



Five-leaved Clover (fig. 120). — Another instance of the chance 

 occurrence of an ever-sporting variety in a dormant condition is the five- 

 leaved clover. The four-bladed clover leaf is of common occurrence. If 

 one isolates such plants and breeds from them, two things may happen. 

 Either there is hardly any progress and four leaves remain rare, or there 

 is a sudden improvement which may easily be worked up into a variety 

 extraordinarily rich in leaves of the more compound type. In this case, 

 a hidden instance of the ever- sporting variety was accidentally caught. I 

 had the good luck of finding such a promising individual twenty years 

 ago, and from it produced, in a few years, a variety which is wholly 

 constant, although extremely dependent on conditions of good treatment. 



Oenothera Lamarckiana var. nanella (fig. 121). — My last instance 

 is the large-flowered evening primrose, a plant which is producing 

 annually about a dozen new forms. I do not say that, in the long run, 

 it produces indefinite numbers of varieties, but that the same novelties 

 spring from it almost every year. This, however, is a most curious 

 feature and gives us the means of studying the origin of new forms in 

 all its details. It allows the repetition of experiments as often as may 

 be wished, and the study of the influence of all kinds of external 

 conditions upon the phenomenon. For about twenty years I have 

 followed this process, cultivating hundreds of thousands of single plants. 



The most remarkable variety is a dwarf which reaches scarcely half 

 the size of the normal plant, and which begins to flower when only about 

 four inches high. Its flowers, however, are almost as large as those of 

 the parent species. From this you see that it is a very showy little plant. 

 In order to display its full beauty, it has to be cultivated as a biennial, 

 since annual specimens are ordinarily too weak. It produces an abun- 

 dance of seeds, which, when purely fertilized, reproduce the variety 

 without exception. 



The interesting feature of this dwarf, however, is the fact of its 

 repeated production by the parent species. It appears annually, even 

 when cross-pollination is carefully excluded. Moreover, it appears in 

 relatively considerable numbers, one or two of every hundred seedlings 

 being dwarfs. These are easily detected, even when still very young 

 plants with only a few leaves. 



Oenothera Lamarckiana. ■ Mutation in the lata family (fig. 122). — 

 Besides the dwarfs, other new types occur, and they also can be de- 

 tected in the seedling stage. In the first place, we have the var. lata, 

 which betrays itself by broader leaves with rounded tips and of a paler 

 green. It never becomes as tall as the parent plant, and is easily dis- 

 tinguished by its weak stems and bending tips. Another common type 

 has narrow and almost whitish leaves : thence its name of albida. It 

 is the most easily recognized deviation among the seedlings, but also 

 the most difficult one to cultivate on account of its almost insufficient 

 supply of chlorophyll. 



