Allergenic Weeds of Maryland

Pollen allergens with hyperlinks are available in GREER's catalog. Click on the allergen that you are interested in and connect with that item in GREER's catalog.

To learn more about a particular pollen allergen, click on the PDF icon [] of that allergen. These botanical profiles are available for download and include a detailed profile, genus/species and family, location(s) found in the United States and photograph(s) of the pollen.

Marked Cells () signify taxon present in area. Unmarked Cells signify taxon absent in area or unconfirmed.

1 Cross-reactive species grouped together in colored cells
2 Italicized species demonstrate only moderate cross-reactivity with other(s) in the group
3 This species is insect-pollinated

Most weeds pollinate in the fall.

	Mountains			Piedmont				Western Shore				Eastern Shore
Cross-Reactive Weeds 1
32: Careless Weed	x	x		x	x	x		x	x	x		x	x
52: Pigweed, Rough/Redroot :	x	x		x	x	x		x	x	x		x	x
53: Pigweed, Spiny :	x	x		x	x	x		x	x			x
35: Dock, Yellow :	x	x		x	x	x		x	x	x		x	x
64: Sorrel, Sheep/Red :	x	x		x	x	x		x	x	x		x	x
55: Ragweed, Giant :	x	x		x	x	x		x	x	x		x	x
56: Ragweed, Short :	x	x		x	x	x		x	x	x		x	x
Other Weeds
225: Baccharis :								x	x	x		x	x
33: Cocklebur :	x	x		x	x	x		x	x	x		x	x
184: Dog Fennel :										x		x	x
43: Lamb's Quarter :	x	x		x	x	x		x	x	x		x	x
Mexican Tea	x	x		x	x	x		x	x	x		x	x
47: Mugwort, Common :	x	x		x	x	x		x	x	x		x	x
36: Nettle :	x	x		x	x	x		x
54: Plantain, English :	x	x		x	x	x		x	x	x		x	x
59: Russian Thistle :										x		x	x

Data obtained from USDA Plants Database.

For current pollen counts visit www.pollen.com or enter a zip code below.

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