PATROGENESIS 
A Form of Inheritance with the Characters of the Female Parent Completely 
Excluded—A Cross Between Two Genera of Grasses, Tripsacum 
and Euchlaena' 
G. N. Coiitns anp J. H. KEMPTON 
Bureau of Plant Industry, U. S. Department of Agriculture, Washington, D. C. 
INTRODUCTION 
FERTILE hybrid between Trip- 
A cecin dactyloides L. and Euchlaena 
mexicana Schrad., was reported 
by the writers in 1914. The 
behavior of the single first generation 
plant was at that time described and its 
close resemblance to the male parent 
noted.? 
It is now possible to report the be- 
havior of the progeny of this hybrid 
plant, which have been grown for two 
seasons, and to make comparisons with 
the first generation plant and with the 
parents. 
The parental stocks were Tripsacum 
dactyloides and Euchlaena mexicana. 
Tripsacum is a perennial grass native 
in many parts of eastern United States 
and is of no economic importance. 
Euchlaena is an annual grass native in 
Mexico and frequently grown in the 
United States for forage under the 
name of “teosinte.’’ These species not 
only belong to different genera, but are 
placed in separate groups of the tribe 
Maydeae. The two genera, together 
with Maize or Indian corn, are the only 
American representatives of the tribe. 
The plants differ profoundly in general 
appearance, as well as in structural 
details, as the illustrations show. 
The list of contrasted characters given 
on the opposite page will serve to indi- 
cate the more conspicuous differences. 
The plant of Euchlaena used as the 
male parent in the hybrid was from seed 
received from Dr. H. V. Jackson, of 
Durango, Mexico. Euchlaena is re- 
ported as a wild plant about Durango. 
It is also cultivated in the same region. 
The cultivated form, at least, is much 
hybridized with maize. Plants repre- 
senting all stages from what appears 
to be pure Euchlaena to those that 
closely resemble pure maize have been 
grown from original seed received from 
that region. 
The fact that the particular plant 
used as pollen parent of the cross was 
grown in the greenhouse, where Eu- 
chlaena plants never behave normally, 
made it difficult to determine whether 
this plant shared any of the frequent 
contamination with maize. The plant 
was stunted and somewhat abnormal, 
but no maize characters could be 
observed, and there has been a similar 
absence of maize-like characters in the 
pure seed progeny of the hybrid plant. 
It is, therefore, believed that the male 
parent of the hybrid represented a 
relatively pure form of Euchlaena. 
DESCRIPTION OF SUPPOSED HYBRID 
The original cross was made in 
March, 1913, in a greenhouse of the 
Department of Agriculture at Washing- 
ton, the Euchlaena pollen being placed 
on the stigmas of a plant of Tripsacum. 
Precautions were taken to guard against 
foreign pollen, although no other Trip- 
sacum plants were growing in the 
greenhouse and no pollen was yet 
being produced on the plant that was 
fertilized, Tripsacum being decidedly 
proterogenous. The cross was such a 
violent one that there was little expecta- 
tion of success, but four seeds developed 
and these were planted as soon as 
mature. Whenasprout appeared above 
' Read before the twelfth annual meeting of the American Genetic Association, at Berkeley, 
Cal., August 6, 1915. 
* Collins, G. N.,and Kempton, J. H., A Hybrid between Tripsacum and Euchlaena. Journal 
Washington Academy Science, Volume IV, No. 5, pp.-114-117, March 4, 1914. 
106 
