''Pyrola'' is a genus of evergreen

herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of ...

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

s in the family

Ericaceae The Ericaceae () are a Family (biology), family of flowering plants, commonly known as the heath or heather family, found most commonly in acidic and infertile growing conditions. The family is large, with about 4,250 known species spread acros ...

. Under the old Cronquist system it was placed in its own family

Pyrolaceae Pyroloideae is a subfamily of plants in the family Ericaceae. It was formerly treated as a separate family, Pyrolaceae.Stevens, P.F. (2001 onwards).Ericaceae ''Angiosperm Phylogeny Website''. Retrieved 2014-12-29. It has also been treated as the t ...

, but genetic research showed it belonged in the family

. The species are commonly known as wintergreen, a name shared with several other related and unrelated plants (see

wintergreen Wintergreen is a group of aromatic plants. The term ''wintergreen'' once commonly referred to plants that remain green (continue photosynthesis) throughout the winter. The term ''evergreen'' is now more commonly used for this characteristic. ...

for details). They are native to northern temperate and

Arctic The Arctic (; . ) is the polar regions of Earth, polar region of Earth that surrounds the North Pole, lying within the Arctic Circle. The Arctic region, from the IERS Reference Meridian travelling east, consists of parts of northern Norway ( ...

regions. They are rather small plants with a rosette of simple orbicular or ovate

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

, with a

flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

stem bearing generally rather lax

raceme A raceme () or racemoid is an unbranched, indeterminate growth, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are ...

s of simple white, cream or pink flowers. The immediate distinguishing feature of ''Pyrola'' species is the flower style which is often curved, sticks out beyond the petals and is expanded below the stigma which itself is branched into several lobes. To the casual observer the flower appears to have a small bell-clapper sticking out.

Distribution

They are distributed across northern

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

and

arctic The Arctic (; . ) is the polar regions of Earth, polar region of Earth that surrounds the North Pole, lying within the Arctic Circle. The Arctic region, from the IERS Reference Meridian travelling east, consists of parts of northern Norway ( ...

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

and

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

. In North America they also occur down the western mountains south to

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

Reproduction

Pyrolaceae, as part of the Ericales produce

pollen Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...

anther The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

s which open by apical pores. The pollen itself is produced in tetrads and is rather ''sticky''. Not surprisingly, wintergreens are

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

pollinated, most commonly by

flies Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwin ...

. The rather large and complex stigma may be an adaptation to ensure that small insects carrying pollen have an attractive landing place. The flowers are produced in the summer and the rather inconspicuous greenish seed capsules are produced in the autumn. The seeds are numerous and very small.

Ecology

Wintergreens prefer damp and shady locations in woods or in

dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat ...

slacks. They are often rather local in distribution but can be locally common especially in their more northern locations. Occurring often separately from the leaved varieties are the achlorophyllous, leafless forms of one or more of the typed species. Leaves, if present, can be narrow and reddish. These are myco-heterotrophs and feed parasitically off of one or more of the local mycelia. Because of this parasitic action, the viability of the non-photosynthetic pyrola relies on the survival of the supporting mycelium. The pyrola group is one of a select few that can live both photosynthetically or not. This differentiation is not understood and if deciphered could explain how other obligate non-photosynthetic forest dwelling plants have crossed that evolutionary threshold. Captain George Vancouver's (1757-1798) botanist Archibald Menzies discovered four new pyrolas near Squirrel Cove, Cortes Island, BC with delicate pink or white flowers often with evergreen leaves. From Desolation Sound by Heather Harbord 1939

Pharmacology

''Pyrola elliptica'', commonly known as "shinleaf", contains a drug related to

aspirin Aspirin () is the genericized trademark for acetylsalicylic acid (ASA), a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and inflammation, and as an antithrombotic. Specific inflammatory conditions that aspirin is ...

, and the leaves have been used to treat bruises. Its common name derives from its use in shin casting.

References

External links

{{Taxonbar, from=Q157528 Ericaceae genera Flora of Europe Flora of Northern America Flora of temperate Asia Taxa named by Carl Linnaeus