RESIN–RUBBER FROM CANADIAN GROWN PLANTS: I. VARIATION IN SELECTED GENERA

1944 ◽  
Vol 22f (6) ◽  
pp. 199-207
Author(s):  
R. W. Watson ◽  
N. H. Grace
Keyword(s):  
Gradual Increase ◽  
Growing Season ◽  
Asclepias Syriaca ◽  
Rubber Content ◽  
The Common ◽  
Common Milkweed Asclepias Syriaca

The common milkweed, Asclepias syriaca L. was selected from the most promising native genera as the only species with a resin–rubber content high enough to warrant extraction studies. Rubber is concentrated in the leaves. Drying milkweed under glass in air and full daylight at temperatures up to 60 °C. does not reduce the rubber content. Concentrates are produced by fermentative decomposition. There is a gradual increase in the leaf rubber content during the growing season, with a maximum of about 3.5% in late September in the Ottawa district.

Plant-insect relationships between common milkweed Asclepias syriaca (Gentianales: Asclepiadacees) and the European skipper Thymelicus lineola (Lepidoptera: Hesperiidae)

1977 ◽  
Vol 55 (11) ◽  
pp. 1553-1555 ◽  
Author(s):  
Jeremy N. McNeil
Keyword(s):  
Insect Pest ◽  
Asclepias Syriaca ◽  
The Common ◽  
Common Milkweed Asclepias Syriaca

European skipper adults aggregate on common milkweed and their legs and (or) proboscis often become entangled in the flowers. Occasionally this results in the loss of legs or in the death of the insect. Normally the insects escape unharmed and frequently carry with them milkweed pollinia, attached to the extremity of their tarsi. Thus the European skipper, an insect pest, may act as a pollinating agent of a weed pest, the common milkweed.

scholarly journals Multiple paternity in Asclepias syriaca using a paired-fruit analysis

1995 ◽  
Vol 73 (8) ◽  
pp. 1212-1216 ◽  
Author(s):  
Julie J. Gold ◽  
Joel S. Shore
Keyword(s):  
Maximum Likelihood ◽  
Key Words ◽  
Multiple Paternity ◽  
Statistical Evidence ◽  
Likelihood Methods ◽  
Asclepias Syriaca ◽  
Maximum Likelihood Methods ◽  
Fruit Abortion ◽  
The Common ◽  
Common Milkweed Asclepias Syriaca

We investigated the extent of multiple paternity within and between fruits of the common milkweed, Asclepias syriaca, at one site. Using isozyme polymorphisms at four loci and the maximum likelihood methods of Williams and Evarts (1989), we found no statistical evidence for multiple paternity within fruits. When pairs of fruits obtained from individual ramets were analyzed in a similar manner, extensive multiple paternity was observed, indicating that fruits on the same ramet are sired by different paternal parents. This extensive multiple paternity between fruits provides considerable opportunity for maternal choice via selective fruit abortion. Key words: Asclepias, isozyme polymorphisms, multiple paternity, pollinia.

scholarly journals Ecogeographical determinants of the ecological niche of the common milkweed (Asclepias syriaca) on the basis of indices of remote sensing of land images

2016 ◽  
Vol 24 (1) ◽  
pp. 78-86
Author(s):  
O. M. Kunah ◽  
O. S. Papka
Keyword(s):  
Land Surface ◽  
Ecological Niche ◽  
Vegetation Index ◽  
Principal Component ◽  
Vegetative Cover ◽  
Asclepias Syriaca ◽  
Water Index ◽  
The Common ◽  
Common Milkweed Asclepias Syriaca ◽  
Vegetative Indices

The patterns of variation in vegetative indices received by means of data of remote land sensing are described as being dependant on geomorphological predictors and the sizes of agricultural fields in an experimental polygon within Poltava region. The possibilities of application of vegetative indices have been explored through ecogeographical determinants of the ecological niche of the common milkweed (Asclepias syriaca L.) and other weeds. On the basis of images of the land surface taken on 23 March and 27 August 2015 by the sensor control Operational Land Imager (OLI), installed on the satellite Landsat 8, vegetative indices have been calculated (AC-Index – aerosol/coastal index, Hydrothermal Composite, NDTI – Normalized Difference Tillage Index, NDVI – Normalized Difference Vegetation Index, VI – Vegetation Index, MNDW – Modified Normalized Difference Water Index, LSWI – Land Surface Water Index, NBR – Normalized Burn Ratio, M15). The data obtained have been subjected to principal component analysis and the revealed principal components have been interpreted with the help of regression analysis, in which geomorphological variables have been applied as predictors. It was possible to explain the trends of variability of the vegetative cover, formalized in the form of the principal component, by means of indices which quantitatively characterise features of relief. The various aspects of variation of vegetative cover have been shown to be characterised by the specificity of the influence of relief factors. A prominent aspect of the variation of the vegetative cover of agroecosystems is variability within a field. The degree of a variation of conditions is proportional to the size of a field. Large fields occupy level plain positions. In turn, within small fields sources of variation are changes in ecological conditions which arise owing to unevenness of relief, which increases in proximity to gullies and ravines. We have identified the aspects of the variation of vegetative cover which by their nature can be considered as contributers to the growth of weeds in agroceonoses. Satellite imaging by Landsat does not allow direct identification of concentrations of weeds, but it can reveal complex changes in the landscape cover, which act as markers of the processes connected with development of weed vegetation. The procedure of further decoding of satellite images for the purpose of identification of weeds requires greater attention in this field of research.

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