By: H. Wayne Shew, Ph.D.
NAB Certified Pollen Counter
AAAC Collection Station—Birmingham, Alabama
Pasture with lots of plantain and bahia grass. Dark heads are plantain inflorescences.
Plantago pollen – note multiple pores in the pollen grains (periporate), and annulus and operculum.
Plantagoplant with basal rosette of leaves and several flower stalks arising from this rosette.
Plantago is an herbaceous to subshrub plant that is found all over the world (America, Asia, Australia, Africa, Europe) in a variety of habitats. This genus includes numerous species (about 250), many of which can be described as cosmopolitan weeds. These plants are commonly found in wet areas such as bogs or seepages but can also be found in alpine and semi-alpine as well as coastal areas, and often can be found in large numbers along roadsides and in fields and pastures. Plantains succeed in practically any soil but prefer sunny over full shade locations. Plantains are perennials that grow from a short rootstock or rhizome. A large number of straight roots grow from the rhizome deep into the soil. Plants have a basal rosette of leaves and produce flower stalks from the center of this rosette. Depending upon the species of Plantago, the leaves may be narrow and grass like, to broadly oval in shape.
Plantago plants are wind-pollinated and produce large amounts of pollen that is released into the air to become part of the aerospora. The pollen is allergenic and is one of the pollen types that we monitor at the pollen collection station located at Alabama Asthma and Allergy in Homewood, Alabama. The pollen of plantain is spherical in shape and is periporate, meaning that it has numerous pores present, typically 8-14. The pores have an annulus and a covering over the center of the pore called an operculum. The pollen of the two most widely distributed species, P. lanceolata and P. major, range in size from 25-30 microns. Individuals known to be allergic to plantain should consider reducing outdoor activities during May and June, the time of maximum bloom by the most common species. Of course, this is also the timeframe during which grass pollen is normally elevated so there could be additional reasons to take care when participating in outside activities during these months.
Plantain has leaf margins that are entire (no teeth present) or are unevenly toothed. The leaves vary in length depending on the species but typically are strong and fibrous with 3-7 ribbed veins which contract into a long petiole. Flower stalks arise from the basal rosette of leaves and are erect, slender, and bear densely-flowered spikes. The flowers are tiny and each is bell-shaped with four stamens; the anthers are purple. The fruit is a two-celled capsule that bears 4-16 seeds. The two species mentioned above can produce as many as 15,000 seeds per plant. Plantain seeds are small (1.5 – 3.5 mm), oval, reddish-brown, and nearly tasteless. They are quite tough and can remain viable in the soil for up to 60 years. The seeds also survive passage through the gut of birds and other animals which facilitates their distribution. They are coated with mucilage which also aids in their transportation by adhesion to various surfaces.
Plantain has been used since prehistoric times as a food, (leaf vegetable and salad) and in herbal remedies. It is astringent and has antimicrobial and anti-inflammatory properties. It has been used as an expectorant and demulcent, as well as for treatment of coughs and bronchitis. Externally, the leaves have been used to treat insect bites, minor cuts and sores, boils, and poison-ivy rashes. The seed coat expands and becomes mucilaginous when wet. This characteristic makes plantain, particularly the species P. psyllium, a common over-the-counter bulk laxative and fiber supplement product. Plantain is useful in the treatment of constipation, irritable bowel syndrome, and diverticular disease. For additional information on the use of plantain in herbal medications, I recommend checking out various herbals and ethnobotany books and websites devoted to these topics. Alternative Nature Online Herbal is one such site. For those desiring a more in depth, scientific discussion of this plant, then try websites such as Science Direct However, be aware that this site provides only abstracts of chapters in a book. To read entire chapters in the book requires you to purchase the book or individual chapters from the publisher.
Note:This is one of a series of blogs that describes some of the common species of plants that produce pollen in our area that are known to serve as allergens. It is a good idea to know what the plants look like that produce pollen that act as allergens and try to avoid having them around where you live if possible, and to know when they are producing pollen in the area where you live.