STERILITY IN LILIES 



A. B. Stout 

 New York Botanical Garden, Nezv Ycrk City 



THE tendency of many species of 

 lilies to produce seed irregularly, 

 sparingly, or even not at all, is 

 well exemplified in the old familiar 

 Tiger Lily of our flower gardens. This 

 species has been in cultivation in Eu- 

 rope since 1804 ; it thrives and blooms 

 abundantly over a wide area ; it has 

 been observed in cultivation and also 

 apparently wild in its native home 

 (China and Japan) by persons inter- 

 ested in discovering whether fruits 

 were formed. Yet the author is aware 

 of only two references to the pods and 

 seeds of this species, and the accuracy 

 of these is somewhat doubtful. On 

 the other hand, its fruitlessness has 

 repeatedly been observed wherever it 

 has been grown. The Tiger Lily is one 

 of the most striking examples that can 

 be cited of a plant which blooms in 

 abundance but is propagated only by 

 vegetative means. 



The Law of Compensation 



A ready explanation has long been 

 offered by gardeners and botanists for 

 the condition of sterility found in such 

 plants as the lilies. It has been gener- 

 ally believed that they are physically 

 unable to develop seeds because the 

 bulbs and bulblets use the available 

 food. The tiny embryos were assumed 

 to be virtually starved to death. This 

 explanation of the condition has seemed 

 so obvious and so correct that it has 

 received the sanction of the most crit- 

 ical authorities, and is stated in Dar- 

 win's law of compensation and in 

 Goebel's law of correlation. But this 

 simple and apparently very satisfactory 

 explanation we now know to be entirely 

 wrong, at least in its application to the 

 condition of sterility in the lilies. 

 Obviously the best evidence of the 



truth of this statement is the fact that 

 these usually fruitless plants have been 

 shown to be fully able to produce 

 capsules and seeds. Such evidence is 

 in most cases readily obtained. 



Sterility Due to Incompatibility of 

 Pollen 



For a period of about fifteen years 

 Focke persisted in attempts to obtain 

 seed of L. hulhifenmi. He secured 

 bulbs from various parts of northern 

 and western Germany and made many 

 cross-pollinations of their flowers, but 

 obtained at best only a few poor cap- 

 sules. Finally, bulbs were secured 

 from Switzerland and with the use of 

 pollen of plants grown from them pods 

 and seeds in abundance were matured 

 on the hitherto fruitless plants.^ 



The writer has had much the same 

 experience with other species of lilies. 

 A fine large cluster of L. croceum, all 

 descended from a single bulb, growing 

 in the New York Botanical Garden, 

 completely failed to set seed for eight 

 consecutive years. The numerous 

 flowers that appeared each year 

 were self- and cross-pollinated, but 

 there was never even a slight en- 

 largement of any of the ovaries. In 

 1 92 1, plants of L. elegans bloomed 

 at the same time as the cluster of 

 L. crocemn, and their pollen was 

 used in pollinations. Fine large pods 

 then developed, and these contained 

 many viable seeds. In 1922 these 

 plants of L. croc cum also yielded ' 

 pods and seed by cross-pollina- 

 tion with another strain of the same 

 species. Hence these plants were fully 

 able to mature fruit, and their pollen 

 was likewise able to function in cer- 

 tain reciprocal crosses. 



^ Several papers by W. O. Focke bearing on phenomena of self-incompatibility were pub- 

 lished between the years 1887 and 1893. 



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