Trillium grandiflorum
Encyclopedia
Trillium grandiflorum, commonly known as white trillium, great white trillium, white wake-robin, or in French
as trille blanc, is a perennial monocotyledonous plant in the lily family
. It is native to eastern North America
, from northern Quebec
to the southern parts of the United States
through the Appalachian Mountains
into northernmost Georgia
and west to Minnesota
. It also thrives on Vancouver Island
in British Columbia
. There are also several disjunctive populations, such as in Nova Scotia
and Iowa
. The plant is most common in rich deciduous and mixed upland forests. It is easily recognised by its attractive three-petaled white flowers, opening from the late spring to the early summer, that rise above a whorl
of three, leaf-like bract
s.
Trillium grandiflorum has been studied extensively by ecologists due to a number of unique features it possess. It is a representative example of a plant whose seeds are spread through myrmecochory
, or ant-mediated dispersal, which is effective in increasing the plant's ability to outcross, but ineffective in bringing the plant very far. This has led ecologists to question how it and similar plants were able to survive glaciation events during the ice ages. The height of the species has also been shown to be an effective index of how intense foraging by deer is in a particular area.
Some forms of the species have pink instead of white petals, while others with extra petals, also called "double" forms, are naturally quite common in the species, and these are especially popular with Trillium gardeners. In fact, the species is the most popular of its genus in cultivation, which has led to conservation concerns due to the majority of commercially available plants being collected from the wild. A few regional governments in Canada and the United States have declared the plant vulnerable as a result. As the plant is attractive and well known, it serves as the provincial emblem of Ontario
, the state wild flower of Ohio
, and it is often used in heraldry
in Canada
.
and produces a single, showy white flower
atop a whorl of three leaves. These leaves are ovate
(i.e., egg-shaped) in outline with pointed tips. They lack petiole
s (or have extremely short ones) and measure 12–20 cm long by 8–15 cm wide (58 in long by 3–6 in width), with very prominently engraved venation. The leaves and the stem share a dark green color and persist into autumn. Leaves and petals both have somewhat undulate margins, the leaves often much more strongly so. Individuals grow to between about 15 and 30 cm tall (6–12 inches). A single rootstock will often form clonal colonies, which can become very large and dense.
The erect, odorless flowers are large, especially compared to other species of Trillium, with 4 to 7 cm (1.5 to 2.7 in) long petal
s, depending on age and vigor. The petals are shaped much like the leaves and curve outward. They have a visible venation, though this is nowhere near as marked as on the leaves. Their overlapping bases and curve give the flower a distinctive funnel
shape. Between the veined petals, three acuminate (ending with a long point) sepal
s are visible; they are usually a paler shade of green than the leaves, and are sometimes streaked with maroon. Flowers are perched on a pedicel
(i.e., flower stalk) raising them above the leaf whorl, and grow pinker as they age.
Flowers have six stamen
s in two whorls of three, which persist
after fruiting. The style
s are white and very short compared to the 9–27 mm (0.5–1 in) anthers, which are pale yellow but becomes a brighter shade when liberating pollen
due to the latter's color. The ovary
is six-sided with 3 greenish-white stigmas that are at first weakly attached, but fuse higher up. The fruit is a green, mealy and moist orb, and is vaguely six-sided like the ovary.
in his 1803 work Flora Boreali-Americana. T. rhomboideum is now a synonym of the closely related species T. erectum
. T. grandiflorum was first treated as a species by Richard Anthony Salisbury
only two years later. The species was traditionally placed in the subgenus
Trillium, but recent work has shown the phylogeny of this grouping to be paraphyletic. Since then no phylogeny of the genus has garnered much agreement (The other subgenus, Phyllantherum, includes sessile-flowered species). T. grandiflorum is, alongside the western T. ovatum
, one of the closer relatives to the subg. Phyllantherum members.
One form
of the plant, T. grandiflorum f. roseum, opens with light pink petals instead of the common white. It is generally found very rarely throughout the range, but in the Blue Ridge Mountains
of Virginia
is can be found somewhat frequently in mixed or sometimes pure colonies. It should be noted that the white flowers of the common pure white variety of T. grandiflorum turn a very distinctive pink and remain so for several days just prior to the wilting of the flowers. Plants bearing these pink flowers are often mistaken for a "pink variety" of trillium.
Many variants of T. grandiflorum have green markings on the petals, as well as anywhere from 4 to 30 extra petals or bracts along with other highly deformed characteristics. Although many of these forms have been given taxonomic names, it has been shown that mycoplasma
-like bacteria are responsible for the altered morphology in these individuals and not genetic variation
. T. grandiflorum does, however, occasionally produce double-flowered
forms such as T. g. f. polymerum. These are almost invariably sterile, but are much sought after for their appearance by trillium growers. It is the species of trillium that produces double flowers most frequently. On the other hand, and unlike other species such as T. erectum which hybridize fairly easily, T. grandiflorum is not known to form hybrids.
or beech
forests, but has also been known to spread into nearby open areas. Depending on geographical factors, it flowers from late April to early June, just after T. erectum. Like many forest perennials, T. grandiflorum is a slow growing plant. Its seeds require double dormancy, meaning they normally take at least two years to fully germinate
. Like most species of Trillium, flowering age is determined largely by the surface of the leaf and volume of the rhizome the plant has reached instead of age alone. Because growth is very slow in nature, T. grandiflorum typically requires seven to ten years in optimal conditions to reach flowering size, which corresponds to a minimum of 36 cm² (5.6 sq in) of leaf surface area and 2.5 cm³ (0.152439024390244 cu in) of rhizome volume. In cultivation, however, wide disparity of flowering ages are observed.
Due to the popularity of Trillium grandiflorum as a garden specimen, conservation concerns have been raised as the vast majority of plants sold in commercial nurseries are believed to be collected from the wild. Indeed, there is little indication of any commercial nursery growth. Frederick and Roberta Case, botanists who specialize in trilliums, wrote in 1997, "to our knowledge, no true commercial quantity 'propagation' takes place at the present time." Such heavy collecting, combined with other pressures such as habitat destruction and grazing, may effectively endanger the plants in some areas.Trillium grandiflorum is legally listed as vulnerable in Quebec
, primarily due to habitat destruction as the plant is found in forests neighboring the province's most populous regions. It is listed as exploitably vulnerable in the state of New York
, meaning that it might become threatened should certain factors not be mitigated. In Maine
, it is listed as endangered, and might have been extirpated entirely.
Trillium grandiflorum has long been thought to self-pollinate based on the fact that pollinators had rarely been observed visiting the plants and because there is low variation in chromosomal banding patterns. This has been strongly challenged, as other studies have shown high pollination rates by bumblebee
s and very low success of self-pollination in controlled experiments, implying that they are in fact self-incompatible. Several ovule
s of a given individual often fail to produce seeds. One contributing factor is pollen limitation, and one study showed that open pollinated plants had 56% of their ovules produce seeds, while in hand pollinated individuals the figure was 66%. Plants with reduced exposure to pollinators were 33% to 50% less likely to produce fruits than those that were, while hand pollinated individuals showed a 100% fruit set (though these fruits did not contain a 100% seed set). Plant resources were shown to be a limiting factor in seed production: when pollen was in abundance, larger plants had a significantly greater seed to ovule ratio than smaller ones. The overall suboptimal seed to ovule ratios suggest that Trillium grandiflorum has evolved to maximize reproductive success in the face of highly stochastic
pollination, where some plants may only be visited by a single pollinator in a season.
Fruits are released in the summer, containing about 16 seeds on average. These seeds are most typically dispersed by ant
s, which is called myrmecochory
, but yellow jackets (Vespula vulgaris) and harvestmen (order Opiliones) have both been observed dispersing the seeds at lower frequencies. Insect dispersal is aided by the presence of a conspicuous elaiosome
, an oil-rich body attached to the seed, which is high in both lipid
s and oleic acid
. The oleic acid induces corpse-carrying behavior in ants, causing them to bring the seeds to their nesting sites as if they were food. As ants visit several colonies of the plant, they bring genetically variable seeds back to a single location, which after germination results in a new population with relatively high genetic diversity
. This has the ultimate effect of increasing biological fitness.
Although myrmecochory is by far the most common dispersal method, white-tailed deer
have also been shown to disperse the seeds on rare occasions by ingestion and defecation. While ants only move seeds up to about 10 meters, deer have been observed to transport the seeds over 1 kilometer. This helps to explain post-agricultural colonization of forest sites by Trillium grandiflorum, as well as long distance gene flow
which has been detected in other studies. Furthermore, it helps resolve what has been called "Reid's paradox", which states that migration during glaciation events
must have been impossible for plants with dispersal rates under several hundred meters per year, such as Trillium grandiflorum. Thus occasional long distance dispersal events, such as by deer, probably helped save this and other species with otherwise short distance dispersal ability from extinction during the glaciations of the ice ages. Furthermore, nested clade
analysis of cpDNA haplotypes has shown that Trillium grandiflorum is likely to have persisted through the last glacial period in two sites of refuge in the southeastern United States
and that long distance dispersal was responsible for the post-glacial recolonization of northern areas.
. Indeed if trilliums are available deer will seek these plants, with a preference for T. grandiflorum, to the exclusion of others. In the course of normal browsing, deer consume larger individuals, leaving shorter ones behind. This information can be used to assess deer density and its effect on understory growth in general.
When foraging intensity increases, individuals become shorter each growing season due to the reduction in energy reserves from less photosynthetic production. One study determined that the ideal deer density in northeastern Illinois
, based on T. grandiflorum as an indicator of overall understory health, is 4 to 6 animals per square kilometer. This is based on a 12 to 14 cm stem height as an acceptable healthy height. In practice, deer densities as high as 30 deer per square kilometers are known to occur in restricted or fractured habitat where natural control mechanisms (that is, predators like wolves) are lacking. Such densities, if maintained over more than a few years, can be very damaging to the understory and lead to extinction of some local understory plant populations.
As a particularly conspicuous forest flower, T. grandiflorum was designated the provincial emblem of Ontario
in 1937 (Flora Emblem Act), and as the state wild flower of Ohio
in 1987. As the symbol of Ontario, a stylized trillium flower features prominently on the official flag of the province's French-speaking community
. It is also frequently used by the Canadian Heraldic Authority
to represent Ontario in grants of arms. Although a network of laws make picking wildflowers in general illegal in the province more often than not, it is not, unlike widely believed, specifically illegal (or necessarily harmful) to pick the species in Ontario.
T. grandiflorum is one of the most popular trilliums in cultivation, primarily because of the size of its flowers and its relative ease of cultivation. Although not particularly demanding, its cultivation is a slow and rather uncertain process, due to usually slow growth, wide variations in growth speed and sometimes capricious germination rates. As a result, the vast majority of plants and rhizomes in commerce are collected in the wild, and such heavy collecting, combined with other pressures such as habitat destruction and grazing, may effectively endanger the plants in some areas. This also creates tensions between Trillium enthusiasts and conservation proponents. Transplantation (as with almost all non-weedy wild plants) is a delicate process, and in many cases results in the death of the plant. In cultivation, T. grandiflorum may flower in as little as 4 to 5 years after germination (compared to the usual 7 to 10 in the wild), but these cases appear to be exceptions rather than the rule. One study revealed 20 or so individuals performing so well out of about 10,000 seeds planted, only 20% of which germinated after a year. However, barring plant destruction, T. grandiflorum can continue flowering every year after it has begun.
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...
as trille blanc, is a perennial monocotyledonous plant in the lily family
Liliaceae
The Liliaceae, or the lily family, is a family of monocotyledons in the order Liliales. Plants in this family have linear leaves, mostly with parallel veins but with several having net venation , and flower arranged in threes. Several have bulbs, while others have rhizomes...
. It is native to eastern North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, from northern Quebec
Quebec
Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....
to the southern parts of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
through the Appalachian Mountains
Appalachian Mountains
The Appalachian Mountains #Whether the stressed vowel is or ,#Whether the "ch" is pronounced as a fricative or an affricate , and#Whether the final vowel is the monophthong or the diphthong .), often called the Appalachians, are a system of mountains in eastern North America. The Appalachians...
into northernmost Georgia
Georgia (U.S. state)
Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...
and west to Minnesota
Minnesota
Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...
. It also thrives on Vancouver Island
Vancouver Island
Vancouver Island is a large island in British Columbia, Canada. It is one of several North American locations named after George Vancouver, the British Royal Navy officer who explored the Pacific Northwest coast of North America between 1791 and 1794...
in British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
. There are also several disjunctive populations, such as in Nova Scotia
Nova Scotia
Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...
and Iowa
Iowa
Iowa is a state located in the Midwestern United States, an area often referred to as the "American Heartland". It derives its name from the Ioway people, one of the many American Indian tribes that occupied the state at the time of European exploration. Iowa was a part of the French colony of New...
. The plant is most common in rich deciduous and mixed upland forests. It is easily recognised by its attractive three-petaled white flowers, opening from the late spring to the early summer, that rise above a whorl
Whorl
A whorl is a type of spiral or circular pattern.Other meanings of whorl include:* Whorl , used to describe the attachment of sepals, petals, leaves, or branches at a single point...
of three, leaf-like bract
Bract
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis, or cone scale. Bracts are often different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture...
s.
Trillium grandiflorum has been studied extensively by ecologists due to a number of unique features it possess. It is a representative example of a plant whose seeds are spread through myrmecochory
Myrmecochory
Myrmecochory is seed dispersal by ants, an ecologically significant ant-plant interaction with worldwide distribution. Myrmecochorous plants produce seeds with elaiosomes, a term encompassing various external appendages or "food bodies" rich in lipids, amino acid, or other nutrients that are...
, or ant-mediated dispersal, which is effective in increasing the plant's ability to outcross, but ineffective in bringing the plant very far. This has led ecologists to question how it and similar plants were able to survive glaciation events during the ice ages. The height of the species has also been shown to be an effective index of how intense foraging by deer is in a particular area.
Some forms of the species have pink instead of white petals, while others with extra petals, also called "double" forms, are naturally quite common in the species, and these are especially popular with Trillium gardeners. In fact, the species is the most popular of its genus in cultivation, which has led to conservation concerns due to the majority of commercially available plants being collected from the wild. A few regional governments in Canada and the United States have declared the plant vulnerable as a result. As the plant is attractive and well known, it serves as the provincial emblem of Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....
, the state wild flower of Ohio
Ohio
Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...
, and it is often used in heraldry
Heraldry
Heraldry is the profession, study, or art of creating, granting, and blazoning arms and ruling on questions of rank or protocol, as exercised by an officer of arms. Heraldry comes from Anglo-Norman herald, from the Germanic compound harja-waldaz, "army commander"...
in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
.
Description
T. grandiflorum is a perennial that grows from a short rhizomeRhizome
In botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...
and produces a single, showy white flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
atop a whorl of three leaves. These leaves are ovate
Leaf shape
In botany, leaf shape is characterised with the following terms :* Acicular : Slender and pointed, needle-like* Acuminate : Tapering to a long point...
(i.e., egg-shaped) in outline with pointed tips. They lack petiole
Petiole (botany)
In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...
s (or have extremely short ones) and measure 12–20 cm long by 8–15 cm wide (58 in long by 3–6 in width), with very prominently engraved venation. The leaves and the stem share a dark green color and persist into autumn. Leaves and petals both have somewhat undulate margins, the leaves often much more strongly so. Individuals grow to between about 15 and 30 cm tall (6–12 inches). A single rootstock will often form clonal colonies, which can become very large and dense.
The erect, odorless flowers are large, especially compared to other species of Trillium, with 4 to 7 cm (1.5 to 2.7 in) long petal
Petal
Petals are modified leaves that surround the reproductive parts of flowers. They often are brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are usually accompanied by another set of special leaves called sepals lying...
s, depending on age and vigor. The petals are shaped much like the leaves and curve outward. They have a visible venation, though this is nowhere near as marked as on the leaves. Their overlapping bases and curve give the flower a distinctive funnel
Funnel
A funnel is a pipe with a wide, often conical mouth and a narrow stem. It is used to channel liquid or fine-grained substances into containers with a small opening. Without a funnel, spillage would occur....
shape. Between the veined petals, three acuminate (ending with a long point) sepal
Sepal
A sepal is a part of the flower of angiosperms . Collectively the sepals form the calyx, which is the outermost whorl of parts that form a flower. Usually green, sepals have the typical function of protecting the petals when the flower is in bud...
s are visible; they are usually a paler shade of green than the leaves, and are sometimes streaked with maroon. Flowers are perched on a pedicel
Pedicel (botany)
A pedicel is a stem that attaches single flowers to the main stem of the inflorescence. It is the branches or stalks that hold each flower in an inflorescence that contains more than one flower....
(i.e., flower stalk) raising them above the leaf whorl, and grow pinker as they age.
Flowers have six stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...
s in two whorls of three, which persist
Marcescence
Marcescence is the retention of dead plant organs that normally are shed. It is most obvious in deciduous trees that retain leaves through the winter. Several trees normally have marcescent leaves such as oak , beech and hornbeam . Marcescent leaves of pin oak complete development of their...
after fruiting. The style
Gynoecium
Gynoecium is most commonly used as a collective term for all carpels in a flower. A carpel is the ovule and seed producing reproductive organ in flowering plants. Carpels are derived from ovule-bearing leaves which evolved to form a closed structure containing the ovules...
s are white and very short compared to the 9–27 mm (0.5–1 in) anthers, which are pale yellow but becomes a brighter shade when liberating pollen
Pollen
Pollen 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 from the stamens to the pistil of flowering plants or from the male cone to the...
due to the latter's color. The ovary
Ovary (plants)
In the flowering plants, an ovary is a part of the female reproductive organ of the flower or gynoecium. Specifically, it is the part of the pistil which holds the ovule and is located above or below or at the point of connection with the base of the petals and sepals...
is six-sided with 3 greenish-white stigmas that are at first weakly attached, but fuse higher up. The fruit is a green, mealy and moist orb, and is vaguely six-sided like the ovary.
Taxonomy
Trillium grandiflorum was originally described as T. rhomboideum var. grandiflorum by André MichauxAndré Michaux
André Michaux was a French botanist and explorer.-Biography:Michaux was born in Satory, now part of Versailles, Yvelines. After the death of his wife within a year of their marriage he took up the study of botany and was a student of Bernard de Jussieu...
in his 1803 work Flora Boreali-Americana. T. rhomboideum is now a synonym of the closely related species T. erectum
Trillium erectum
Trillium erectum, also known as Wake-robin, red trillium, purple trillium, Beth root or Stinking Benjamin, is a spring-flowering perennial plant native to the east and north-eastern areas of North America. The flowers are a deep red colour, and the plant takes its name Wake-robin by analogy with...
. T. grandiflorum was first treated as a species by Richard Anthony Salisbury
Richard Anthony Salisbury
Richard Anthony Salisbury FRS was a British botanist. While he is remembered as a valuable worker in horticultural and botanical sciences, several bitter disputes caused him to be ostracised by his contemporaries.-Life:...
only two years later. The species was traditionally placed in the subgenus
Subgenus
In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...
Trillium, but recent work has shown the phylogeny of this grouping to be paraphyletic. Since then no phylogeny of the genus has garnered much agreement (The other subgenus, Phyllantherum, includes sessile-flowered species). T. grandiflorum is, alongside the western T. ovatum
Trillium ovatum
Trillium ovatum, the Western Wake Robin, Pacific Trillium, or Western White Trillium, is a member of the Trilliaceae family, or sometimes included within the Liliaceae or Melanthiaceae. It occurs in parts of the western United States and western Canada, usually in rich forest...
, one of the closer relatives to the subg. Phyllantherum members.
Form (botany)
In botanical nomenclature, a form is one of the "secondary" taxonomic ranks, below that of variety, which in turn is below that of species; it is an infraspecific taxon...
of the plant, T. grandiflorum f. roseum, opens with light pink petals instead of the common white. It is generally found very rarely throughout the range, but in the Blue Ridge Mountains
Blue Ridge Mountains
The Blue Ridge Mountains are a physiographic province of the larger Appalachian Mountains range. This province consists of northern and southern physiographic regions, which divide near the Roanoke River gap. The mountain range is located in the eastern United States, starting at its southern-most...
of Virginia
Virginia
The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...
is can be found somewhat frequently in mixed or sometimes pure colonies. It should be noted that the white flowers of the common pure white variety of T. grandiflorum turn a very distinctive pink and remain so for several days just prior to the wilting of the flowers. Plants bearing these pink flowers are often mistaken for a "pink variety" of trillium.
Many variants of T. grandiflorum have green markings on the petals, as well as anywhere from 4 to 30 extra petals or bracts along with other highly deformed characteristics. Although many of these forms have been given taxonomic names, it has been shown that mycoplasma
Mycoplasma
Mycoplasma refers to a genus of bacteria that lack a cell wall. Without a cell wall, they are unaffected by many common antibiotics such as penicillin or other beta-lactam antibiotics that target cell wall synthesis. They can be parasitic or saprotrophic. Several species are pathogenic in humans,...
-like bacteria are responsible for the altered morphology in these individuals and not genetic variation
Genetic variation
Genetic variation, variation in alleles of genes, occurs both within and among populations. Genetic variation is important because it provides the “raw material” for natural selection. Genetic variation is brought about by mutation, a change in a chemical structure of a gene. Polyploidy is an...
. T. grandiflorum does, however, occasionally produce double-flowered
Double-flowered
"Double-flowered" describes varieties of flowers with extra petals, often containing flowers within flowers. The double-flowered trait is often noted alongside the scientific name with the abbreviation fl. pl....
forms such as T. g. f. polymerum. These are almost invariably sterile, but are much sought after for their appearance by trillium growers. It is the species of trillium that produces double flowers most frequently. On the other hand, and unlike other species such as T. erectum which hybridize fairly easily, T. grandiflorum is not known to form hybrids.
Ecology
T. grandiflorum favors well-drained, neutral to slightly acid soils, usually in second- or young-growth forests. In the Northern parts of its range it shows an affinity for mapleMaple
Acer is a genus of trees or shrubs commonly known as maple.Maples are variously classified in a family of their own, the Aceraceae, or together with the Hippocastanaceae included in the family Sapindaceae. Modern classifications, including the Angiosperm Phylogeny Group system, favour inclusion in...
or beech
Beech
Beech is a genus of ten species of deciduous trees in the family Fagaceae, native to temperate Europe, Asia and North America.-Habit:...
forests, but has also been known to spread into nearby open areas. Depending on geographical factors, it flowers from late April to early June, just after T. erectum. Like many forest perennials, T. grandiflorum is a slow growing plant. Its seeds require double dormancy, meaning they normally take at least two years to fully germinate
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...
. Like most species of Trillium, flowering age is determined largely by the surface of the leaf and volume of the rhizome the plant has reached instead of age alone. Because growth is very slow in nature, T. grandiflorum typically requires seven to ten years in optimal conditions to reach flowering size, which corresponds to a minimum of 36 cm² (5.6 sq in) of leaf surface area and 2.5 cm³ (0.152439024390244 cu in) of rhizome volume. In cultivation, however, wide disparity of flowering ages are observed.
Due to the popularity of Trillium grandiflorum as a garden specimen, conservation concerns have been raised as the vast majority of plants sold in commercial nurseries are believed to be collected from the wild. Indeed, there is little indication of any commercial nursery growth. Frederick and Roberta Case, botanists who specialize in trilliums, wrote in 1997, "to our knowledge, no true commercial quantity 'propagation' takes place at the present time." Such heavy collecting, combined with other pressures such as habitat destruction and grazing, may effectively endanger the plants in some areas.Trillium grandiflorum is legally listed as vulnerable in Quebec
Quebec
Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....
, primarily due to habitat destruction as the plant is found in forests neighboring the province's most populous regions. It is listed as exploitably vulnerable in the state of New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
, meaning that it might become threatened should certain factors not be mitigated. In Maine
Maine
Maine is a state in the New England region of the northeastern United States, bordered by the Atlantic Ocean to the east and south, New Hampshire to the west, and the Canadian provinces of Quebec to the northwest and New Brunswick to the northeast. Maine is both the northernmost and easternmost...
, it is listed as endangered, and might have been extirpated entirely.
Pollination and seed dispersal
Bumblebee
A bumble bee is any member of the bee genus Bombus, in the family Apidae. There are over 250 known species, existing primarily in the Northern Hemisphere although they are common in New Zealand and in the Australian state of Tasmania.Bumble bees are social insects that are characterised by black...
s and very low success of self-pollination in controlled experiments, implying that they are in fact self-incompatible. Several ovule
Ovule
Ovule means "small egg". In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: The integument forming its outer layer, the nucellus , and the megaspore-derived female gametophyte in its center...
s of a given individual often fail to produce seeds. One contributing factor is pollen limitation, and one study showed that open pollinated plants had 56% of their ovules produce seeds, while in hand pollinated individuals the figure was 66%. Plants with reduced exposure to pollinators were 33% to 50% less likely to produce fruits than those that were, while hand pollinated individuals showed a 100% fruit set (though these fruits did not contain a 100% seed set). Plant resources were shown to be a limiting factor in seed production: when pollen was in abundance, larger plants had a significantly greater seed to ovule ratio than smaller ones. The overall suboptimal seed to ovule ratios suggest that Trillium grandiflorum has evolved to maximize reproductive success in the face of highly stochastic
Stochastic
Stochastic refers to systems whose behaviour is intrinsically non-deterministic. A stochastic process is one whose behavior is non-deterministic, in that a system's subsequent state is determined both by the process's predictable actions and by a random element. However, according to M. Kac and E...
pollination, where some plants may only be visited by a single pollinator in a season.
Fruits are released in the summer, containing about 16 seeds on average. These seeds are most typically dispersed by ant
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...
s, which is called myrmecochory
Myrmecochory
Myrmecochory is seed dispersal by ants, an ecologically significant ant-plant interaction with worldwide distribution. Myrmecochorous plants produce seeds with elaiosomes, a term encompassing various external appendages or "food bodies" rich in lipids, amino acid, or other nutrients that are...
, but yellow jackets (Vespula vulgaris) and harvestmen (order Opiliones) have both been observed dispersing the seeds at lower frequencies. Insect dispersal is aided by the presence of a conspicuous elaiosome
Elaiosome
Elaiosomes are fleshy structures that are attached to the seeds of many plant species. The elaiosome is rich in lipids and proteins, and may be variously shaped. Many plants have elaiosomes to attract ants, which take the seed to their nest and feed the elaiosome to their larvae...
, an oil-rich body attached to the seed, which is high in both lipid
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
s and oleic acid
Oleic acid
Oleic acid is a monounsaturated omega-9 fatty acid found in various animal and vegetable fats. It has the formula CH37CH=CH7COOH. It is an odorless, colourless oil, although commercial samples may be yellowish. The trans isomer of oleic acid is called elaidic acid...
. The oleic acid induces corpse-carrying behavior in ants, causing them to bring the seeds to their nesting sites as if they were food. As ants visit several colonies of the plant, they bring genetically variable seeds back to a single location, which after germination results in a new population with relatively high genetic diversity
Genetic diversity
Genetic diversity, the level of biodiversity, refers to the total number of genetic characteristics in the genetic makeup of a species. It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary....
. This has the ultimate effect of increasing biological fitness.
Although myrmecochory is by far the most common dispersal method, white-tailed deer
White-tailed Deer
The white-tailed deer , also known as the Virginia deer or simply as the whitetail, is a medium-sized deer native to the United States , Canada, Mexico, Central America, and South America as far south as Peru...
have also been shown to disperse the seeds on rare occasions by ingestion and defecation. While ants only move seeds up to about 10 meters, deer have been observed to transport the seeds over 1 kilometer. This helps to explain post-agricultural colonization of forest sites by Trillium grandiflorum, as well as long distance gene flow
Gene flow
In population genetics, gene flow is the transfer of alleles of genes from one population to another.Migration into or out of a population may be responsible for a marked change in allele frequencies...
which has been detected in other studies. Furthermore, it helps resolve what has been called "Reid's paradox", which states that migration during glaciation events
Glacial motion
Glacial motion is the motion of glaciers, which can be likened to rivers of ice. It has played an important role in sculpting many landscapes. Most lakes in the world occupy basins scoured out by glaciers...
must have been impossible for plants with dispersal rates under several hundred meters per year, such as Trillium grandiflorum. Thus occasional long distance dispersal events, such as by deer, probably helped save this and other species with otherwise short distance dispersal ability from extinction during the glaciations of the ice ages. Furthermore, nested clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
analysis of cpDNA haplotypes has shown that Trillium grandiflorum is likely to have persisted through the last glacial period in two sites of refuge in the southeastern United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and that long distance dispersal was responsible for the post-glacial recolonization of northern areas.
Interaction with deer
Trillium grandiflorum as well as other trilliums are a favored food of white-tailed deerWhite-tailed Deer
The white-tailed deer , also known as the Virginia deer or simply as the whitetail, is a medium-sized deer native to the United States , Canada, Mexico, Central America, and South America as far south as Peru...
. Indeed if trilliums are available deer will seek these plants, with a preference for T. grandiflorum, to the exclusion of others. In the course of normal browsing, deer consume larger individuals, leaving shorter ones behind. This information can be used to assess deer density and its effect on understory growth in general.
When foraging intensity increases, individuals become shorter each growing season due to the reduction in energy reserves from less photosynthetic production. One study determined that the ideal deer density in northeastern Illinois
Illinois
Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...
, based on T. grandiflorum as an indicator of overall understory health, is 4 to 6 animals per square kilometer. This is based on a 12 to 14 cm stem height as an acceptable healthy height. In practice, deer densities as high as 30 deer per square kilometers are known to occur in restricted or fractured habitat where natural control mechanisms (that is, predators like wolves) are lacking. Such densities, if maintained over more than a few years, can be very damaging to the understory and lead to extinction of some local understory plant populations.
Culture and uses
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....
in 1937 (Flora Emblem Act), and as the state wild flower of Ohio
Ohio
Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...
in 1987. As the symbol of Ontario, a stylized trillium flower features prominently on the official flag of the province's French-speaking community
Franco-Ontarian
Franco-Ontarians are French Canadian or francophone residents of the Canadian province of Ontario. They are sometimes known as "Ontarois"....
. It is also frequently used by the Canadian Heraldic Authority
Canadian Heraldic Authority
The Canadian Heraldic Authority is part of the Canadian honours system under the Queen of Canada, whose authority is exercised by the Governor General. The Authority is responsible for the creation and granting of new coats of arms , flags and badges for Canadian citizens, permanent residents and...
to represent Ontario in grants of arms. Although a network of laws make picking wildflowers in general illegal in the province more often than not, it is not, unlike widely believed, specifically illegal (or necessarily harmful) to pick the species in Ontario.
T. grandiflorum is one of the most popular trilliums in cultivation, primarily because of the size of its flowers and its relative ease of cultivation. Although not particularly demanding, its cultivation is a slow and rather uncertain process, due to usually slow growth, wide variations in growth speed and sometimes capricious germination rates. As a result, the vast majority of plants and rhizomes in commerce are collected in the wild, and such heavy collecting, combined with other pressures such as habitat destruction and grazing, may effectively endanger the plants in some areas. This also creates tensions between Trillium enthusiasts and conservation proponents. Transplantation (as with almost all non-weedy wild plants) is a delicate process, and in many cases results in the death of the plant. In cultivation, T. grandiflorum may flower in as little as 4 to 5 years after germination (compared to the usual 7 to 10 in the wild), but these cases appear to be exceptions rather than the rule. One study revealed 20 or so individuals performing so well out of about 10,000 seeds planted, only 20% of which germinated after a year. However, barring plant destruction, T. grandiflorum can continue flowering every year after it has begun.