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w16 Rough marshelder

Whole Allergen
Code w16
LOINC 6232-3
Family Asteraceae ⁄ Compositae
Genus Iva L.
Species Iva annua/ciliata
Route of Exposure Inhalation
Source Material Pollen
Latin Name Iva ciliate / Iva annua
Other Names Rough Marsh Elder, Annual Marshelder, Annual Marsh-Elder, Sumpweed
Categories Weed Pollens


Rough marshelder (Iva annua) is a coarse-textured plant that grows to a height of around 1-4 feet. This plant is abundantly found in lakes, river bottoms, valleys, lowlands, and damp areas. This weed pollen is predominantly found in the US and extends to Mexico. Rough marshelder pollen can trigger allergic conditions like asthma, allergic rhino-conjunctivitis, and allergic rhinitis. No allergenic proteins from rough marshelder pollen have been identified in the IUIS database. Rough marshelder pollen exhibits cross-reactivity with pollen from short ragweed and ragweed.



Rough marshelder (Iva annua) is a coarse-textured plant (1) that usually attains a height of around 1-4 feet (2). This plant typically possesses a single stem and a flowering spike with heads holding pistillate and staminate flowers. The stem of rough (true) marshelder is generally purple or green with a lined surface texture, while the sap is colorless. Oppositely arranged leaves are commonly found in young marshelder plants, while with aging, alternately arranged leaves might appear at the extreme top. The pollination period for rough marshelder is concurrent to short ragweed (2). During the prehistoric period, the seeds from rough marshelder species have been consumed due to their high nutritional (consists of numerous vitamins and minerals) and calorific (2500 calories/pound) value (3).


Rough marshelder (Iva annua) usually thrives near lakes, river bottoms, valleys, lowlands, damp areas (1) and is reported to be moderately salt-tolerant (4). Although rough marshelder is found to prefer damp or wet soil conditions, it has been reported to sustain in various other soil conditions like an alkaline marsh, deeply rich, sandy, alluvial, clay, and others (1). 


Iva annua (rough marshelder), earlier known by I.Ciliata wild, belongs to the Compositae family (1). Rough mash elder has been claimed to be closely associated (botanically) to ragweed (species of genera Ambrosia) (2). 

Taxonomic tree of  Rough marshelder (5)
Domain Eukaryota
Kingdom Plantae
Phylum Spermatophyta
Subphylum Magnoliophyta 
Class Magnoliopsida
Order Asterales
Family Asteraceae ⁄ Compositae
Genus Iva L.
Species Iva annua/ciliata


A study has reported rough marshelder pollen to be slightly larger compared to common ragweed pollen (average diameter: 20 µ) (2). Detailed published information on the structure of marshelder pollen is not available.

No allergenic protein from rough marshelder pollen has been characterized in the IUIS database (6).


Worldwide distribution

A study confirmed [through skin prick test (SPT) and/or serum specific-IgE] marshelder to be one of the seasonal weed pollen allergens found in the southeast regions of the United States (US) (7).

In a US-based retrospective study, 43.6% (24/55) of patients demonstrated positive SPT towards rough marshelder pollen (allergen) (8).

A Saudi-Arabian based study was conducted on 1159 patients (>5years; with respiratory allergy, allergic rhinitis, and/or bronchial asthma) either from Saudi Arabians or from different nationalities such as western immigrants (majorly North Americans), Indians, Pakistanis, Filipinos, and other Arabian countries. Marshelder pollen has been revealed to be one of the contributors for frequent pollen-mediated allergic reactions among 23.4% (271/1159) of the patients (9).

Environmental Characteristics

Worldwide distribution

According to a study, marshelder has been found to be prevalent in the United States (majorly of central and eastern regions) and extends till Mexico (south into Tamaulipas) (10). 

Route of Exposure


The route of exposure for rough marshelder pollen is through inhalation (airway) (9).


As per studies, exposure to weed (like marshelder) pollen may induce allergic conditions such as allergic rhinitis (11), allergic rhino-conjunctivitis, and asthma (12). 

Allergic rhinitis (AR) and allergic rhino-conjunctivitis (ARC)

A retrospective analysis conducted on 1137 rhinitis patients (4-79 years) reported marshelder/poverty as one of the most sensitizing weed allergens with a prevalence rate of 27.8% among patients (11).

A Saudi Arabia-based study was conducted on 1159 patients (>5years) with allergic rhinitis, respiratory allergic, and/or bronchial asthma. Marshelder pollen has been reported as one of the pollens responsible for frequent allergic reactions in 23.4% (271/1159) of patients in the study population (9).

A study was conducted on 30 randomly selected patients (with allergic rhino-conjunctivitis and/or asthma) from a total of 78 patients with positive skin prick test (SPT) towards Cannabis. 96% (29/30) of the patients have been observed to possesses positive SPT towards marshelder pollens (12).

Prevention and Therapy

Prevention strategies


Avoiding exposure to a particular allergen is the initial step towards allergic rhinitis management (13).

One of the main measures to reduce the symptoms is to cut down the pollen amounts in the respiratory system. During pollen season, allergic patients are suggested to stay indoors or wear a mask outdoors to keep away from pollen allergens. In worsening conditions, patients may be recommended to move or live in a non-pollen area (14)

Molecular Aspects

Allergenic molecules

To date (21-January-2021), no allergenic molecules from rough marshelder pollen have been listed in the IUIS database (6).


Marshelder has been reported to be cross-reactive with ragweed (15) and short ragweed pollen (16).

Compiled By

Author: Turacoz Healthcare Solutions

Reviewer: Dr. Christian Fischer


Last reviewed: March 2021

  1. Yarnell AR. Iva annua var. macrocarpa: Extinct American Cultigen? American Anthropologist. 1972;74(3):335-41.
  2. Tocker AM. The Possible Role of Iva Ciliara in Hay Fever Therapy. Southern Medical Journal. 1956;49(5).
  3. Cultural Use of Plants from the Baker Wetlands [Internet]. 2002.
  4. Ungar IA, Hogan WC. Seed germination in Iva annua L. Ecology. 1970;51(1):150-4.
  5. USDA. USDA Natural Resources Conservation Service 2021 [18-Jan-2021]. Available from: https://plants.sc.egov.usda.gov/core/profile?symbol=IVANA.
  6. WHO/IUIS. International Union of Immunological Societies Allergen Nomenclature 2021 [21-Jan-2021]. Available from: http://www.allergen.org/search.php?allergensource=roughmarshelder&searchsource=Search.
  7. Pesek RD, Rettiganti M, O'Brien E, Beckwith S, Daniel C, Luo C, et al. Effects of allergen sensitization on response to therapy in children with eosinophilic esophagitis. Ann Allergy Asthma Immunol. 2017;119(2):177-83.
  8. Calhoun KH. Patterns of mold sensitivity in the subtropical Gulf Coast. Otolaryngol Head Neck Surg. 2004;130(3):306-11.
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  10. Smith BD. Eastern North America as an independent center of plant domestication. Proc Natl Acad Sci U S A. 2006;103(33):12223-8.
  11. Calabria CW, Dice JP, Hagan LL. Prevalence of positive skin test responses to 53 allergens in patients with rhinitis symptoms. Allergy Asthma Proc. 2007;28(4):442-8.
  12. Stokes JR, Hartel R, Ford LB, Casale TB. Cannabis (hemp) positive skin tests and respiratory symptoms. Ann Allergy Asthma Immunol. 2000;85(3):238-40.
  13. Fereidouni M, Hossini RF, Azad FJ, Assarehzadegan MA, Varasteh A. Skin prick test reactivity to common aeroallergens among allergic rhinitis patients in Iran. Allergol Immunopathol (Madr). 2009;37(2):73-9.
  14. Xie ZJ, Guan K, Yin J. Advances in the clinical and mechanism research of pollen induced seasonal allergic asthma. Am J Clin Exp Immunol. 2019;8(1):1-8.
  15. Gordon BR. Beginner's Guide to Primary Inhalant Allergens Part 3: Weed and Fern Families. Ear, Nose & Throat Journal. 1994;73(5):306-8.
  16. Perrick D, Stafford CT, Armstrong E, DuRant RH. Modification of the fluorescent allergosorbent test as an inhibition assay for determination of cross-reactivity among aeroallergens. J Allergy Clin Immunol. 1991;87(1 Pt 1):98-103.