Pyrola (syn.
Pirola Necker) is a genus of evergreen
herbaceousA herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...
plantPlants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants,...
s in the family
EricaceaeEricaceae, the heath family or the heather family is a plant family, comprising mostly calcifuge plants that thrive in acidic soils. Many well-known plants of the Ericaceae live in temperate climates, such as cranberry, blueberry, various heaths and heathers , huckleberry, azalea and rhododendron...
. Under the old Cronquist system it was placed in its own family
PyrolaceaePyrolaceae was a small family of flowering plants under the old Cronquist system of plant classification. It included the four genera Chimaphila, Moneses, Orthilia, and Pyrola, and sometimes also the eight genera formerly usually placed in the family Monotropaceae.Recent genetic research by the...
, but genetic research showed it belonged in the family
EricaceaeEricaceae, the heath family or the heather family is a plant family, comprising mostly calcifuge plants that thrive in acidic soils. Many well-known plants of the Ericaceae live in temperate climates, such as cranberry, blueberry, various heaths and heathers , huckleberry, azalea and rhododendron...
. The species are commonly known as
wintergreen, a name shared with several other related and unrelated plants (see
wintergreenWintergreen is a group of plants. Wintergreen once commonly referred to plants that continue photosynthesis throughout the winter...
for details). They are native to northern temperate and
ArcticThe Arctic is the region around the Earth's North Pole, opposite the Antarctic region around the South Pole. The Arctic includes the Arctic Ocean and parts of Canada, Greenland , Russia, the United States , Iceland, Norway, Sweden and Finland.The word Arctic comes from the Greek αρκτικός , "near...
regions.
They are rather small plants with a
rosetteIn botany, a rosette is a circular arrangement of leaves, with all the leaves at a single height.Though rosettes usually sit near the soil, their structure is an example of a modified stem.-Function:...
of simple orbicular or ovate
leavesIn botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin. There is continued debate about whether the flatness of leaves evolved to expose the chloroplasts to more light or to increase the absorption of carbon dioxide. In...
, with a
flowerA flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to mediate the union of male sperm with female ovum in order to produce seeds...
stem bearing generally rather lax
racemeA raceme is a type of inflorescence that is unbranched and indeterminate and bears pedicellate flowers — flowers having short floral stalks called pedicels — along the axis. In botany, axis means a shoot, in this case one bearing the flowers. In a raceme, the oldest flowers are borne...
s of simple white, cream or pink flowers.
Pyrola (syn.
Pirola Necker) is a genus of evergreen
herbaceousA herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...
plantPlants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants,...
s in the family
EricaceaeEricaceae, the heath family or the heather family is a plant family, comprising mostly calcifuge plants that thrive in acidic soils. Many well-known plants of the Ericaceae live in temperate climates, such as cranberry, blueberry, various heaths and heathers , huckleberry, azalea and rhododendron...
. Under the old Cronquist system it was placed in its own family
PyrolaceaePyrolaceae was a small family of flowering plants under the old Cronquist system of plant classification. It included the four genera Chimaphila, Moneses, Orthilia, and Pyrola, and sometimes also the eight genera formerly usually placed in the family Monotropaceae.Recent genetic research by the...
, but genetic research showed it belonged in the family
EricaceaeEricaceae, the heath family or the heather family is a plant family, comprising mostly calcifuge plants that thrive in acidic soils. Many well-known plants of the Ericaceae live in temperate climates, such as cranberry, blueberry, various heaths and heathers , huckleberry, azalea and rhododendron...
. The species are commonly known as
wintergreen, a name shared with several other related and unrelated plants (see
wintergreenWintergreen is a group of plants. Wintergreen once commonly referred to plants that continue photosynthesis throughout the winter...
for details). They are native to northern temperate and
ArcticThe Arctic is the region around the Earth's North Pole, opposite the Antarctic region around the South Pole. The Arctic includes the Arctic Ocean and parts of Canada, Greenland , Russia, the United States , Iceland, Norway, Sweden and Finland.The word Arctic comes from the Greek αρκτικός , "near...
regions.
They are rather small plants with a
rosetteIn botany, a rosette is a circular arrangement of leaves, with all the leaves at a single height.Though rosettes usually sit near the soil, their structure is an example of a modified stem.-Function:...
of simple orbicular or ovate
leavesIn botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat and thin. There is continued debate about whether the flatness of leaves evolved to expose the chloroplasts to more light or to increase the absorption of carbon dioxide. In...
, with a
flowerA flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to mediate the union of male sperm with female ovum in order to produce seeds...
stem bearing generally rather lax
racemeA raceme is a type of inflorescence that is unbranched and indeterminate and bears pedicellate flowers — flowers having short floral stalks called pedicels — along the axis. In botany, axis means a shoot, in this case one bearing the flowers. In a raceme, the oldest flowers are borne...
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
lobeThe term lobe generally refers to a projecting part of an object, but it can have more specific meanings.-Telecommunication:* An identifiable segment of an antenna radiation pattern...
s. To the casual observer the flower appears to have a small bell-clapper sticking out.
Distribution
They are distributed across northern
temperateIn geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally mild, rather than extreme hot or cold. But in continental areas, such as central North America the variations between summer...
and
arcticThe Arctic is the region around the Earth's North Pole, opposite the Antarctic region around the South Pole. The Arctic includes the Arctic Ocean and parts of Canada, Greenland , Russia, the United States , Iceland, Norway, Sweden and Finland.The word Arctic comes from the Greek αρκτικός , "near...
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
,
AsiaAsia is the world's largest and most populous continent, located in the eastern and northern hemispheres. It covers 8.6% of the earth's total surface area and with approximately 4 billion people, it hosts 60% of the world's current human population.Asia is traditionally defined as part of the...
and
North AmericaNorth America is the northern continent of the Americas, situated in the Earth's northern hemisphere and in the western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the west by the North Pacific...
. In North America they also occur down the western mountains south to
CaliforniaCalifornia is the most populous state in the United States, and the third largest by area. California is the second most populous sub-national entity in the Americas, behind only São Paulo, Brazil...
. Some populations in
New EnglandNew England is a region of the United States. It is located at the northeastern corner of the US, bordered by the Atlantic Ocean, Canada and the state of New York, consisting of the modern U.S...
may be introductions by early European settlers.
Reproduction
Pyrolaceae, as part of the Ericales produce
pollenPollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement between the stamens to the pistil of flowering plants or from the male cone to the...
in anthers which open by apical pores. The pollen itself is produced in tetrads and is rather
sticky. Not surprisingly, wintergreens are
insectInsects are arthropods, having a hard exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae. They are the most diverse group of animals on the planet and include more than a million species that are already described. Insects represent more than half of all...
pollinated, most commonly by flies. 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 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.