Spring to Fall
Pollen is usually considered a significant cause of pollinosis, but varies among species within this genus. It is thought that there is considerable cross reactivity among the species within this genus.
Chenopodium plants are annual herbs with an erect or spreading stem that range from 1 to more than 4 feet tall. The leaves are alternate with a length of 1 to 5 inches. The flowers are small and inconspicuous and the fruit is bladder-like. Chenopods grow in open areas and disturbed soil, such as roadsides and dry, sandy areas. The environment (moisture, day length and shade) causes marked differences in the growth form of the plants. The pollen production can range from meager to abundant. In pollen counts, goosefoot and lamb's quarters is often interchanged with the plant called pigweed (Amaranthus) for a few reasons. Flowering and pollen shed occurs at the same time and the pollen grains look very similar to analysts conducting pollen counts through their microscopes. Common names for these plants are also used interchangeably depending on where you are in the country.
The pollen grains of Chenopodium are spheroidal and pantoporate; the pores 20-65 per grain, usually circular, either globally distributed or in luminoid areas separated by muroid ridges; and the opercular granular. The sexine is often tegillate, undulating with a granular surface that is spinulose. The nexine is as thick as or often thinner than the sexine and the intine is generally thick or indistinct.
The pollen grains are 14-50 micrometers in diameter.
The shaded areas on the map indicates where the genus has been observed in the United States.
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