Trillium grandiflorum
Trillium grandiflorum | |
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White trillium blooming in Backus Woods (Ontario, Canada). | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Monocots |
Order: | Liliales |
Family: | Melanthiaceae |
Genus: | Trillium |
Species: | T. grandiflorum
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Binomial name | |
Trillium grandiflorum | |
Synonyms[2] | |
Trillium grandiflorum
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Trillium grandiflorum, the white trillium,
Trillium grandiflorum is most common in rich, mixed upland forests. It is easily recognised by its attractive three-petaled white flowers, opening from late spring to early summer, that rise above a whorl of three leaf-like bracts. It is an example of a spring ephemeral, a plant whose life-cycle is synchronised with that of the deciduous woodland which it favours.
White trillium often occurs in dense drifts of many individuals. The G. Richard Thompson Wildlife Management Area in the Blue Ridge Mountains is renowned for an extensive stand of white trillium that blooms each spring. Over a two square mile area along the Appalachian Trail near Linden, Virginia there is a spectacular annual display of white trilliums estimated at near ten million individuals.[4]
Description
Trillium grandiflorum is a perennial that grows from a short
The erect, odorless flowers are large, especially compared to other species of Trillium, with 4 to 7 cm (1.5 to 3 in) long
Taxonomy
Trillium grandiflorum was first described by André Michaux in 1803 as variety grandiflorum of Trillium rhomboideum,[11] a species now regarded as a synonym of Trillium erectum var. erectum.[12] Michaux described the variety as having broadly rhombic leaves, large white petals, and black fruit.[13] The epithet grandiflorum means "large-flowered",[14] a name that well describes Michaux's variety. In 1805, Richard Anthony Salisbury elevated the variety to a full species.[15][16] As a consequence, and partially by accident, Trillium grandiflorum is commonly known as the large-flowered white trillium.[9]
As of March 2023[update], the name Trillium grandiflorum (Michx.) Salisb. is widely recognized.[2][3][10][17] The species is a member of the Grandiflorum group, a group of species typified by Trillium grandiflorum itself.[18] The group, which also includes Trillium nivale and Trillium ovatum, is sister to a clade comprising subgenus Sessilia (the sessile-flowered trilliums) and subgenus Delostylis (the Catesbaei group).[19]
As of November 2021[update], Plants of the World Online (POWO) lists 20 synonyms for Trillium grandiflorum.[2] Although POWO accepts no infraspecific names, numerous varieties and forms have been described. Of these, perhaps the best known is Trillium grandiflorum f. roseum Farw.,[20][10] which was described by Oliver Atkins Farwell in 1920.[21] The flower of forma roseum opens a striking salmon-pink instead of the more typical white. The pink color of the form is warmer and more attractive than the pink induced by aging. It occurs rarely throughout the range of the species, except along the Blue Ridge Mountains of Virginia where it is locally frequent.[22] The epithet roseum means "rose-like, rose-colored",[23] and so the form is sometimes called the rose trillium.
Trillium grandiflorum, unlike most trilliums, occasionally produces double-flowered forms with more than three petals. T. grandiflorum f. polymerum Vict., a multipetaled form described by Marie-Victorin Kirouac in 1929,[21] occurs rather frequently in this species.[20] Although these wild forms are stable and healthy, the plants usually lack normal floral organs and are therefore completely sterile. The epithet polymerum means "many-parts",[24] which in this case refers to the many flower petals of the form.
Some variants of Trillium grandiflorum have abnormal green markings on the petals (floral virescence), floral organs that take on a leaf-like appearance (phyllody), or other abnormal characteristics. Many of these forms have been given taxonomic names with epithets such as albomarginatum ("white-margined", referring to the petals), foliaceum, ("leaf-like, leafy"), giganteum ("unusually large or tall"), and longipetiolatum ("with long petioles").[2] A typical example is the variety Trillium grandiflorum var. variegatum E.F.Sm., described by Erwin Frink Smith in 1879.[21][25] The epithet variegatum ("streaked or spotted with color") refers to its virescent petals, a distinguishing characteristic of this variety. In 1971, it was shown that mycoplasma-like organisms (now called phytoplasmas) were present in all such forms examined (but not in normal plants). The authors concluded that "such plants should now be regarded as diseased T. grandiflorum and the varietal designation of Smith should be considered invalid."[26]
Unlike other species such as Trillium erectum, which hybridize fairly easily, Trillium grandiflorum is not known to form hybrids.[27]
Ecology
Trillium grandiflorum favors well-drained, neutral to slightly
Pollination and seed dispersal
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 bumblebees and very low success of self-pollination in controlled experiments, implying that they are in fact self-incompatible.[33] Several ovules 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.[34]
Trillium grandiflorum has been studied extensively by ecologists due to a number of unique features it possesses. It is a representative example of a plant whose seeds are spread through
Fruits are released in the summer, containing about 16 seeds on average. These seeds are most typically dispersed by
Although myrmecochory is by far the most common dispersal method,
In addition to the lateral dispersion (by invertebrates and deer) there is also importance in the fact that burial (vertical dispersion) by ants (or other vectors) increases the survival of new plants by two mechanisms. First, vertical dispersion ensures sufficient depth to preserve the seeds through their dormancy (trillium seeds are normally dormant for their first year). Second, vertical dispersion ensures adequate anchorage of the rhizomes. This is particularly important for young plants because their small rhizomes, with few & short roots, are easily dislodged (e.g. frost heaveal and other erosion factors) and desiccated.[37]
Interaction with deer
Trillium grandiflorum as well as other trilliums are a favored food of white-tailed deer. Indeed, if trilliums are available deer will seek these plants, with a preference for T. grandiflorum, to the exclusion of others.[38] 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.[39][40]
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
Disease
Trillium grandiflorum is susceptible to a greening disorder caused by bacterial organisms called phytoplasmas that alter the morphology of infected plants. Symptoms of phytoplasma infection include abnormal green markings on the petals (floral virescence), extra leaves (phyllody), and other abnormal characteristics.[43] Infected populations occur throughout the species range but are prevalent in Ontario, Michigan, and New York.[44]
For many years, this condition was thought to originate from mutation, and so many of these forms were given taxonomic names now known to be invalid. In 1971, Hooper, Case, and Meyers used electron microscopy to detect the presence of mycoplasma-like organisms (i.e., phytoplasmas) in T. grandiflorum with virescent petals. The means of transmission was not established but leafhoppers were suspected.[26] As of November 2021[update], the insect vector for the disorder is unknown.
Phytoplasmas were positively identified in T. grandiflorum and T. erectum in Ontario in 2016 and later confirmed in 2019.
Conservation
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. In Quebec, Trillium grandiflorum is legally listed as vulnerable primarily due to habitat destruction in forests neighboring the province's most populous regions.[47] In New York, Trillium grandiflorum is exploitably vulnerable since it is "likely to become threatened in the near future throughout all or a significant portion of its range within the state if causal factors continue unchecked" (NYCRR §193.3).[citation needed]
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,[48] "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.[49][50]
As of October 2019[update], Trillium grandiflorum is globally secure.[1] The species is vulnerable in Quebec, Georgia, and Illinois; and critically imperiled in Nova Scotia, Alabama, New Jersey, and South Carolina. In Maine, where its presence has not been verified in over 20 years, Trillium grandiflorum is listed as potentially extirpated.[51]
Cultivation
Trillium 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.[49][52] Transplantation (as with almost all non-weedy wild plants) is a delicate process, and in many cases results in the death of the plant.[53] 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.[54] It is winter hardy in USDA zones 4-8.[55]
A double-flowered cultivar,
This plant has gained the Royal Horticultural Society's Award of Garden Merit.[57]
Uses
The leaves were cooked and eaten by some Native Americans. The subterranean rootstalks were also chewed for various medical purposes.[58]
Culture
The large white trillium is a well-known and popular American flower.[43] The Trillium species most often observed by citizen scientists is T. grandiflorum.[59]
The flower's common name, wake-robin, was the title of American naturalist and essayist John Burroughs's first essay collection, Wake-Robin.[60]
As a particularly conspicuous forest flower, T. grandiflorum was designated the provincial floral emblem of
As an official
References
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- ^ a b c d "Trillium grandiflorum (Michx.) Salisb.". Plants of the World Online. Royal Botanic Gardens, Kew. Archived from the original on 10 November 2021. Retrieved 4 November 2021.
- ^ a b USDA, NRCS (n.d.). "Trillium grandiflorum". The PLANTS Database (plants.usda.gov). Greensboro, North Carolina: National Plant Data Team. Retrieved 15 December 2015.
- ^ a b Stritch, Larry. "Great White Trillium (Trillium grandiflorum)". United States Forest Service. Archived from the original on 26 May 2019. Retrieved 1 July 2019.
- ^ "Trillium grandiflorum". County-level distribution map from the North American Plant Atlas (NAPA). Biota of North America Program (BONAP). 2014.
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- ^ Case & Case (1997), p. 99.
- ^ Case & Case (1997), p. 50.
- ^ a b c Case & Case (1997), p. 104.
- ^ a b c d Case Jr., Frederick W. (2002). "Trillium grandiflorum". In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). Vol. 26. New York and Oxford: Oxford University Press – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
- ^ "Trillium rhomboideum var. grandiflorum Michx.". International Plant Names Index (IPNI). Royal Botanic Gardens, Kew; Harvard University Herbaria & Libraries; Australian National Botanic Gardens. Retrieved 2 November 2021.
- ^ "Trillium rhomboideum Michx.". Plants of the World Online. Royal Botanic Gardens, Kew. Archived from the original on 2021-11-05. Retrieved 2021-11-02.
- ^ Michaux, André (1803). "Trillium rhomboideum". Flora Boreali-Americana. 1: 215–216. Archived from the original on 31 October 2021. Retrieved 2 November 2021.
- ^ Gledhill (2008), p. 104.
- ^ "Trillium grandiflorum (Michx.) Salisb.". International Plant Names Index (IPNI). Royal Botanic Gardens, Kew; Harvard University Herbaria & Libraries; Australian National Botanic Gardens. Retrieved 4 November 2021.
- ^ Hooker, William (1805). The Paradisus Londinensis: or Coloured Figures of Plants Cultivated in the Vicinity of the Metropolis. London. Tab. 1. Archived from the original on 2 November 2021. Retrieved 2 November 2021.
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- ^ Lampley (2021), pp. 42.
- ^ a b Case & Case (1997), pp. 107–108.
- ^ a b c Farmer, Susan B. "Named Trilliaceae taxa sorted by genus and species name". goldsword.com. Archived from the original on 4 November 2021. Retrieved 4 November 2021.
- ^ Case & Case (1997), pp. 109–110.
- ^ Gledhill (2008), p. 334.
- ^ Gledhill (2008), pp. 257, 309.
- ^ "Trillium grandiflorum var. variegatum E.F.Sm.". International Plant Names Index (IPNI). Royal Botanic Gardens, Kew; Harvard University Herbaria & Libraries; Australian National Botanic Gardens. Retrieved 7 November 2021.
- ^ a b Hooper, G. R.; Case, F. W. Jr.; Myers, R. (1971). "Mycoplasma-like bodies associated with a flower greening disorder of a wild flower, Trillium grandiflorum". Plant Disease Reporter. 55: 824–828. Archived from the original on 10 November 2021. Retrieved 7 November 2021.
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Bibliography
- Case, Frederick W.; Case, Roberta B. (1997). Trilliums. Portland, Oregon: Timber Press. ISBN 978-0-88192-374-2.
- Gledhill, David (2008). The Names of Plants (4th ed.). Cambridge University Press. ISBN 978-0-521-86645-3.
- Lamoureux, Gisèle (2002). Flore Printanière (in French). Saint-Henri-de-Lévis, Quebec: Fleurbec. pp. 48, 429–449. ISBN 978-2-920174-15-3.
- Lampley, Jayne A. (2021). A systematic and biogeographic study of Trillium (Melanthiaceae) (PhD). University of Tennessee. Retrieved 10 February 2022.
- Lampley, Jayne A.; Gereau, Roy; Floden, Aaron; Schilling, Edward E. (2022-07-05). "A revised subgeneric classification of Trillium (Parideae, Melanthiaceae)". Phytotaxa. 552 (5): 278–286. S2CID 250368253.
External links
- Biodiversity Information Serving Our Nation (BISON) occurrence data and maps for Trillium grandiflorum[permanent dead link]
- Citizen science observations for Large White Trillium at iNaturalist
- Candeias, Matt (June 1, 2021). "When Trillium Flowers Go Green". In Defense of Plants. Retrieved 10 November 2021.
- "Flower-Visiting Insects of Large-Flowered Trillium". Illinois Wildflowers. Retrieved 15 December 2021.