372 



The Journal of Heredity 



In the course of experimental studies 

 with species of Lilium now in progress 

 at the New York Botanical Garden, con- 

 trolled pollinations have been made for 

 plants of twenty-eight species. In 

 every species thus far studied seed 

 production is decidedly limited by in- 

 compatibility in fertilization. 



The phenomena of incompatibility 

 are well illustrated by the results ob- 

 tained with L. regale, a splendid and 

 beautiful lily recently introduced from 

 China. Of the ten plants tested, nine 

 were self-incompatible and one was 

 self -compatible. Cross pollination be- 

 tween plants sometimes succeeded and 

 sometimes failed. The same sort of 

 results were also obtained with plants 

 of L. speciosum, L. candidum, L. 

 henry i, L. parvum, L. tenuifolium, L. 

 humboldtii, L. kelloggii, L. zvarleyense, 

 L. longiflorum, and L. auratum. 



No capsules have yet been obtained 

 on plants of L. hansonii, L. parry i, L. 

 maximowiczii, and L. choice donicum, 

 but in all cases except that of L. han- 

 sonii, only a few plants have been 

 tested, and these were all obtained from 

 a single source. 



Cross-Incompatibility 



It is to be noted that crosses between 

 different plants of a species in which 

 there is self -compatibility are also fre- 

 quently incompatible. One is, however, 

 not at all certain that any two plants 

 of a variety of lily are really of differ- 

 ent seed origin, for they both may be 

 the daughter bulbs of a single parent 

 plant, and thus belong to a single 

 clone. If the original plant grown 

 from seed was entirely self -compatible, 

 then one may expect the members of 

 the clone to fail to set seed in crosses. 

 The condition is similar to that en- 

 countered in fruit-growing, when an 

 entire orchard of a self-incompatible 

 variety of apple or cherry fails to set 

 fruit unless proper cross-pollination 

 with another variety is provided for. 

 Without doubt it is often the extensive 

 vegetative propagation of a single self- 

 incompatible plant that makes it diffi- 

 cult to secure compatible crosses from 



apparently different plants of certain 

 varieties of the day lilies and the true 

 lilies. 



Seedlings of L. longiflorum have 

 been grown to the flowering age in the 

 course of the studies here reported. 

 Many of these were self-incompatible, 

 a few set seed with their own pollen, 

 and many crosses with other plants 

 failed. Such ranges of variation in 

 regard to the compatibilities of sister 

 plants of seed origin are very common 

 in many species. 



Other Types of Sterility 



There are other types of sterility in 

 the lilies besides that of incompatibility. 

 In certain hybrid varieties. L. bate- 

 manniae, for example, there appears to 

 be complete impotence, a type of ster- 

 ility that is very characteristic of hy- 

 brids ; the spores, both in pistils and 

 stamens, are aborted and functionless 

 in any relation. A one-sided abortion 

 characteristic of intersexes has also 

 been noted in at least one species. 



How to Obtain Seed 



The principal condition limiting seed 

 production in the lilies is that of in- 

 compatibility. When seed is desired 

 from plants that are yielding no seeds 

 because of this condition, it is simply 

 necessary to obtain other stocks of the 

 same species and interplant so that 

 cross-pollination may be effected by 

 insects, or by hand. If the new stock 

 is cross-compatible, seed will readily be 

 produced, but if it is not, seed will not 

 be formed until stock which is compat- 

 ible is secured. Usually compatible 

 clones may readily be obtained, and 

 often a single planting of commercial 

 bulbs contains such a mixture of stocks, 

 but for certain species and especially 

 for L. tigrinum, L. hansonii, and L. 

 candidum, it seems somewhat difficult 

 to secure compatible fertilization. 



One of the principal sources of 

 failure in establishing a planting of 

 lilies in one's garden is the poor phys- 

 ical condition of bulbs when received. 

 Especially is this true when bulbs are 

 imported. In many species the dormant 



