Biology, Ecology, and Host Specificity of EuropeanAphthonaspp. (Coleoptera, Chrysomelidae) Used as Biocontrol Agents for Leafy Spurge,Euphorbia esula(Euphorbiaceae), in North America

1996 ◽  
Vol 6 (1) ◽  
pp. 105-113 ◽  
Author(s):  
A. Gassmann ◽  
D. Schroeder ◽  
E. Maw ◽  
G. Sommer
Keyword(s):  
North America ◽  
Host Specificity ◽  
Leafy Spurge ◽  
Biocontrol Agents ◽  
Euphorbia Esula

scholarly journals Release of Postsenescent Dormancy in Leafy Spurge (Euphorbia esula) by Chilling

Weed Science ◽  
1988 ◽  
Vol 36 (6) ◽  
pp. 784-786 ◽  
Author(s):  
Stephen J. Harvey ◽  
Robert M. Nowierski
Keyword(s):  
Growth Rate ◽  
North America ◽  
Growth And Development ◽  
Leafy Spurge ◽  
Climatic Conditions ◽  
Euphorbia Esula ◽  
Flower Buds ◽  
Significant Growth ◽  
Number Of Stems

The growth and development of leafy spurge (Euphorbia esulaL. #3EPHES) collected during postsenescent dormancy and grown in the greenhouse was increasingly stimulated by chilling treatments longer than 14 days duration at 0 to 6 C. Production of stems with flower buds, primary flowers, and secondary flowers was greater in plants chilled for 42 days or more. The effects of chilling on total number of stems, number of strictly vegetative stems, or number of stems with vegetative branching were not significant. The height of the tallest stem per pot was influenced by chilling longer than 42 days. Growth rate also increased as a function of chilling duration. Based on our findings, we believe that there is little possibility that any significant growth can occur in the postsenescent period because of the prevailing climatic conditions found in areas of leafy spurge distribution in North America.

Morphometric studies of the Euphorbia esula group (Euphorbiaceae) in North America

1990 ◽  
Vol 68 (9) ◽  
pp. 1978-1988 ◽  
Author(s):  
C. W. Crompton ◽  
A. E. Stahevitch ◽  
W. A. Wojtas
Keyword(s):  
North America ◽  
Morphological Characters ◽  
Leafy Spurge ◽  
Principal Coordinate Analysis ◽  
Euphorbia Esula ◽  
Eastern North America ◽  
Single Variable ◽  
Authentic Material ◽  
Variable Species ◽  
Euphorbia Cyparissias

Leafy spurge and cypress spurge are important weeds of pastures and unimproved rangeland in western and eastern North America, respectively. Taxonomists disagree as to whether leafy spurge is a single variable species or an aggregate of two or more species. Morphometric techniques (clustering by incremental sum of squares and principal coordinate analysis) were used to analyze relationships in leafy spurge and its allies. On the basis of studying 26 morphological characters found in 200 collections representing 32 putative taxa, we concluded that in North America only four species should be recognized, namely, Euphorbia agraria Bieb., Euphorbia cyparissias L., Euphorbia esula L., and Euphorbia ×pseudoesula Schur. A key to these taxa is provided. No authentic material of Euphorbia lucida Waldst. & Kitt. and Euphorbia salicifolia Host was found from this continent in the collections we examined.

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