Flora of Georgia and surrounding states
Trilliums!
While there are many endemic plants that I could choose to represent the Southeast, trilliums are always the first that come to mind. Of the 50 or so species found in the world, 29 are found in the Southeast as the major center of distribution, and 22 in Georgia, the most of any state. For this reason, the Georgia Botanical Society uses the trillium as part of its logo.
Trilliums as a group are extremely easy to recognize. Their very name comes from their flower construction with everything in 3's. Each plant has but a single flower with whorls of a 3-carpelled pistil, 6 stamens, 3 petals, 3 sepals and 3 bracts, all distinct and unconnected. The flowers either rise above the bracts on a stalk (the pedicellate trilliums) or sit right on the bracts (the sessile trilliums). The leaves of all but the far west pedicillate trillums are plain green while the sessile trilliums have mottled leaves. Recognizing the species of Trillium is not so easy. Even in 1817 botanist Steven Elliott wrote "this family is an interesting one. A whorl of leaves at the summit of a stem, supporting a single flower, it contains and conceals many species."
Taxonomy
Ah, what to do with all the lilies! They have been recognized as being a garbage can mess for a long time with many clearly not very closely related plants. Agaves are surely very different that Easter lilies and they are very different from sawbriers, yet all have been considered members of the same, very broadly circumscribed family, the Liliaceae of Linnæus. Trilliums have broad, net-veined leaves, unique among this group.
Modern phylogenetic studies have helped clarify some of the issues, and there is a slowly growing consensus about many of the new families being carved out of the old LIliaceae. There are still many things to work out. Trilliums are one of them. Perhaps the most widely followed phylogeny is that of the Angiosperm Phylogeny Group or APG. Under their APG III system, trilliums are included in the Melanthiaceae in tribe Paridae with the caveat that "the backbone of the phylogeny in Parideae remains distinctly poorly supported". My friend Susan Farmer along with Ed Schilling argue convincingly (for me at least) that they deserve their own family, while stating "Trilliaceae have been easy to circumscribe but difficult to place". This is not a new idea as the family was first recognized in 1827 when French botanist François Fulgis Chevallier (1796-1840) named it. Many current references (such as Weakley) use the 1846 circumscription of John Lindley FRS (1799-1865), English botanist, gardener and orchidologist and use his name as author.
As a family, Trilliaceae includes six genera:
Paris, with China as its center of diversity but ranging through Europe to Iceland, is notable for having mostly 4-merous flower.
Daiswa, of eastern Asia.
Trillium, with the southeastern United States as its center of diversity but occurring in the Pacific northwest and eastern Asia.
Trillidium, a monotypic genus from the Himalayan Mountains that is probably basal to the entire family.
Kinugasa, a monotypic genus from Japan.
Pseudotrillium, a monotypic genus from the Siskiyou Mountains of California and Oregon.
In the southeastern United States we have only the genus Trillium. Trilliums are a lovely group to learn to love and enjoy. If you want them for your garden, please be sure you secure them from a reputable source that doesn't poach from the wild (a real problem).
Etymology
Derived from Old Swedish thrīr to Sweedish trilling to Latin trilix, triple-woven, triple to New Latin, trillium. All are based on the number 3, which defines the number of all parts of the trillium plant.
Distribution
Trilliums as a group are extremely easy to recognize. Their very name comes from their flower construction with everything in 3's. Each plant has but a single flower with whorls of a 3-carpelled pistil, 6 stamens, 3 petals, 3 sepals and 3 bracts, all distinct and unconnected. The flowers either rise above the bracts on a stalk (the pedicellate trilliums) or sit right on the bracts (the sessile trilliums). The leaves of all but the far west pedicillate trillums are plain green while the sessile trilliums have mottled leaves. Recognizing the species of Trillium is not so easy. Even in 1817 botanist Steven Elliott wrote "this family is an interesting one. A whorl of leaves at the summit of a stem, supporting a single flower, it contains and conceals many species."
Taxonomy
Ah, what to do with all the lilies! They have been recognized as being a garbage can mess for a long time with many clearly not very closely related plants. Agaves are surely very different that Easter lilies and they are very different from sawbriers, yet all have been considered members of the same, very broadly circumscribed family, the Liliaceae of Linnæus. Trilliums have broad, net-veined leaves, unique among this group.
Modern phylogenetic studies have helped clarify some of the issues, and there is a slowly growing consensus about many of the new families being carved out of the old LIliaceae. There are still many things to work out. Trilliums are one of them. Perhaps the most widely followed phylogeny is that of the Angiosperm Phylogeny Group or APG. Under their APG III system, trilliums are included in the Melanthiaceae in tribe Paridae with the caveat that "the backbone of the phylogeny in Parideae remains distinctly poorly supported". My friend Susan Farmer along with Ed Schilling argue convincingly (for me at least) that they deserve their own family, while stating "Trilliaceae have been easy to circumscribe but difficult to place". This is not a new idea as the family was first recognized in 1827 when French botanist François Fulgis Chevallier (1796-1840) named it. Many current references (such as Weakley) use the 1846 circumscription of John Lindley FRS (1799-1865), English botanist, gardener and orchidologist and use his name as author.
As a family, Trilliaceae includes six genera:
Paris, with China as its center of diversity but ranging through Europe to Iceland, is notable for having mostly 4-merous flower.
Daiswa, of eastern Asia.
Trillium, with the southeastern United States as its center of diversity but occurring in the Pacific northwest and eastern Asia.
Trillidium, a monotypic genus from the Himalayan Mountains that is probably basal to the entire family.
Kinugasa, a monotypic genus from Japan.
Pseudotrillium, a monotypic genus from the Siskiyou Mountains of California and Oregon.
In the southeastern United States we have only the genus Trillium. Trilliums are a lovely group to learn to love and enjoy. If you want them for your garden, please be sure you secure them from a reputable source that doesn't poach from the wild (a real problem).
Etymology
Derived from Old Swedish thrīr to Sweedish trilling to Latin trilix, triple-woven, triple to New Latin, trillium. All are based on the number 3, which defines the number of all parts of the trillium plant.
Distribution
Farmer, S.B. 2006. Phylogenetic analyses and biogeography of Trilliaceae. Aliso: A Journal of Systematic and Evolutionary Botany 22:579-592.
Description
Bracts
Trilliums are arranged in whorls of three from the stem up. The first whorl is of three leaf-like bracts. A bract is a leaflike structure that is part of the inflorescence and usually part of the flower whorl series of pistil, stamens, petals, sepals, bracts. Bracts are usually reduced in size from the plant's normal leaves, but these are the only "leaves" of trillium. Since these "leaves" are obviously part of the flower whorl series, they are bracts.
Sepals
The second whorl is of sepals. These usually are the green "bracts" immediately below the petals. In many lilies the sepals look just like the petals and are called petaloid. In red to maroon trilliums, the bracts usually take on some shade of the flowers. They are always much shorter and usually much narrower than the petals.
Petals
The third whorl is of three petals. In the pedicillate (with a stem above the bracts) trilliums the petals are usually as broad as they are long. In the sessile (stalkless) trillums the petals are many times longer than wide and usually more or less erect. The sessile trilliums have mottled leaves and the pedicillate trilliums are a single shade of green (the western Trillium ovatum is the exception to this group, often with mottled leaves). The veins are palmate-reticulate (major veins splitting off a single source but netted in between the veins), very unusual for monocots and especially for lily-like plants.
Stamens
While there are six stamens, a close look at their point of attachment shows that they are in two whorls of three. Where the two halves of the anthers split to open exposing the pollen grains--extrorse (outward), latrorse (on the sides), or introrse (inward)--is an important character to note, especially in the sessile trilliums. The filaments are usually very short and flattened.
Pistil
The uppermost whorl is the female structure and is composed of three carpels and may be three or six-lobed, sometimes appearing almost like wings. The style is very short, usually not discernible between the ovary and stigma. The stigma is divided into three linear sections that can be spreading, twisted or erect. They usually are persistent well into fruiting.
Fruit
The fruit is fleshy and rarely opens along the ridges or wing sutures, but rather by disintegrating at the base. The seeds are 2 to 4 mm long with a white or yellow elaiosome (oil gland) that is very attractive to ants who are a major seed spreading vector making trilliums myrmecochorous.
Species of Trillium
Linnæus named only three:
If the flower sits directly upon the bracts it is Trillium sessile (the stalkless trilliums).
If the flower rises above the bracts on a flower stalk it is Trillium erectum (the erect trilliums).
If the flower nods below the leaves on a flower stalk it is Trillium cernuum (the nodding trilliums).
It is considerably more complicated than that. If you want to learn to tell them apart, good luck! Some are very easy, but many are very difficult. I've said many times that "Only God can make a trillium and only Tom Patrick, John Freeman and Susan Farmer can tell them apart!" Tom is the state botanist for Georgia and a specialist in field study of trilliums, John (now deceased) taught at Auburn University and was a serious field student, and Susan has done extensive systematic and phylogenetic work on them. Weakely and Farmer have an accessible treatment on trilliums here.
Bracts
Trilliums are arranged in whorls of three from the stem up. The first whorl is of three leaf-like bracts. A bract is a leaflike structure that is part of the inflorescence and usually part of the flower whorl series of pistil, stamens, petals, sepals, bracts. Bracts are usually reduced in size from the plant's normal leaves, but these are the only "leaves" of trillium. Since these "leaves" are obviously part of the flower whorl series, they are bracts.
Sepals
The second whorl is of sepals. These usually are the green "bracts" immediately below the petals. In many lilies the sepals look just like the petals and are called petaloid. In red to maroon trilliums, the bracts usually take on some shade of the flowers. They are always much shorter and usually much narrower than the petals.
Petals
The third whorl is of three petals. In the pedicillate (with a stem above the bracts) trilliums the petals are usually as broad as they are long. In the sessile (stalkless) trillums the petals are many times longer than wide and usually more or less erect. The sessile trilliums have mottled leaves and the pedicillate trilliums are a single shade of green (the western Trillium ovatum is the exception to this group, often with mottled leaves). The veins are palmate-reticulate (major veins splitting off a single source but netted in between the veins), very unusual for monocots and especially for lily-like plants.
Stamens
While there are six stamens, a close look at their point of attachment shows that they are in two whorls of three. Where the two halves of the anthers split to open exposing the pollen grains--extrorse (outward), latrorse (on the sides), or introrse (inward)--is an important character to note, especially in the sessile trilliums. The filaments are usually very short and flattened.
Pistil
The uppermost whorl is the female structure and is composed of three carpels and may be three or six-lobed, sometimes appearing almost like wings. The style is very short, usually not discernible between the ovary and stigma. The stigma is divided into three linear sections that can be spreading, twisted or erect. They usually are persistent well into fruiting.
Fruit
The fruit is fleshy and rarely opens along the ridges or wing sutures, but rather by disintegrating at the base. The seeds are 2 to 4 mm long with a white or yellow elaiosome (oil gland) that is very attractive to ants who are a major seed spreading vector making trilliums myrmecochorous.
Species of Trillium
Linnæus named only three:
If the flower sits directly upon the bracts it is Trillium sessile (the stalkless trilliums).
If the flower rises above the bracts on a flower stalk it is Trillium erectum (the erect trilliums).
If the flower nods below the leaves on a flower stalk it is Trillium cernuum (the nodding trilliums).
It is considerably more complicated than that. If you want to learn to tell them apart, good luck! Some are very easy, but many are very difficult. I've said many times that "Only God can make a trillium and only Tom Patrick, John Freeman and Susan Farmer can tell them apart!" Tom is the state botanist for Georgia and a specialist in field study of trilliums, John (now deceased) taught at Auburn University and was a serious field student, and Susan has done extensive systematic and phylogenetic work on them. Weakely and Farmer have an accessible treatment on trilliums here.