Cryptomeric inheritance in Onagra*® 
C. STUART GAGER 
(WITH PLATES 20 AND 21) 
In a previous publication’ I have described an abnormal plant 
of Onagra biennis that appeared in the experimental plot of the 
New York Botanical Garden in a pedigreed culture following 
exposure to radium rays. The seed that produced the plant 
developed in an ovary exposed, before pollination, for 24 hours 
to the 8 and y rays from radium bromid of 10,000 activity con- 
tained in a sealed glass tube. After this exposure the stigma was 
pollinated with unexposed, and, so far as known, normal pollen 
from another pedigreed individual of O. biennis. As described in 
the paper above cited, the seed gave rise to a plant that produced 
two shoot systems of equivalent value; that is, neither could be 
regarded as the main axis of which the other was a lateral branch. 
Apparently each half of the shoot was from a bud axillary in a 
cotyledon. Thus it was held that the anomaly was not a bud 
sport, in the ordinary sense of the word, “‘unless, keeping in mind 
that the plumule is a bud, we decide that there was an early 
bifurcation of the developing embryo, of such a nature that, after 
the cotyledons were laid down, there was a division of the growing 
point, accompanied by a separating out of antagonistic characters, 
and resulting in the formation of two morphologically as well as 
physiologically different shoots.” 
Each half of the seedling (15a of my cultures) developed in 
the usual way, forming a rosette in the seed pan, and subsequently, 
when planted out, sending up a cauline stem from the center of 
each rosette. 
Taxonomic descriptions of the two plants are here repeated 
from the former paper,t and also an illustration of the young 
seedling (FIG. 1). 
* Brooklyn Botanic Garden: Contributions No. 3. 
Loc, cit, 2st. 
461 
