Trillium

Trilliums are native to eastern and western North America and eastern Asia. They are for the most part plants of deciduous forests and are considered to be spring ephemerals, meaning they are herbaceous and die back to the ground in the summer. Their leaves and flower parts are arranged in threes (or multiples thereof), hence the generic name which was selected by Lineaus when he received specimens from eastern North America. Most are well suited to woodland gardens and many are quite hardy even when their native range is quite far south in the USA. Follow this link to the treatment and key for the genus: Trillium in Flora of North America by Fred Case.

• Subgenus Trillium - the pedicillate Trilliums
  • North American Species
  • Asian Species
• Subgenus Phyllantherum - the sessile Trilliums of Eastern and Western North America
• Some Hybrid Trilliums in the Wild
• Trillium diseases

Subgenus Trillium - the pedicillate Trilliums

The genus Trillium contains two subgenera. Sub-genus Trillium contains the pedicillate trilliums (sometimes called pedunculate trilliums) which carry their flowers on pedicels above the leaves. The pedicillate trilliums are native to Eastern and Western North America and to Eastern Asia.

North American Species

Trillium undulatum, the Painted Trillium, is a gorgeous species which grows in cool shady forests in acid soil.

Trillium nivale?, the Snow Trillium, is an adorable little Trillium that is native mainly to the Ohio River Valley in rich stream bottom soils or on rocky limestone hillsides. It is one of the smallest species of trillium. more?

Trillium grandiflorum, the Large-flowered Trillium, is one of the showiest and best known Trilliums. It is also occasionally and confusingly called the snow trillium. It is found growing from Quebec and Ontario (where it is the Provincial Flower) west to Minnesota and south to the Carolinas.

The flowers are pure white which fade to pink and dull red as they get old. Flowers may last more than a week in cool weather. It is not known to hybridize with any other species, but it does vary in size due to a number of factors including: age of the plant, genetics, habitat and occasionally disease. There is a pink flowered form called rorma rosea which has pink flowers upon opening.

• Trillium pusillum?
• The Trillium erectum group?, many if not most of which are known to hybridize, including T. erectum, T. flexipes, T. simile, T. sulcatum, T. cernuum, T. rugellii, and T. vaseyi.
• Trillium catesbaei? - Catesby's Trillium
• Trillium persistans?
• Trillium ovatum?
• Trillium hibbersonii? - also called Tr. ovatum var. hibbersonii

• Trillium rivale? - Recently this species has been reported to be more closely related to the genus paris than to the other species of Trillium and has been moved into a new genus as Pseudotrillium rivale. This change has not yet been reflected in all books or online databases.

Asian Species

• Trillium apetalon?
• Trillium camschatense?
• Trillium hagae?
• Trillium smallii?
• ((Trillium tschonoskiiTrillium tschonoskii))

Subgenus Phyllantherum - the sessile Trilliums of Eastern and Western North America

Sub-genus phyllantherum contains the sessile Trilliums. The flowers sit right down upon the leaves. Trillium albidum, pictured below, is a sessile Trillium. There is one member of this group actually named Trillium sessile and this name has been erroneously applied to a number of other species when they are merely members of this sub-genus.

• Trillium albidum?
• Trillium angustipetalum?
• Trillium chloropetalum?
• Trillium cuneatum?
• Trillium decipiens?
• Trillium decumbens?
• Trillium discolor?
• Trillium foetidissimum?
• Trillium gracile?
• Trillium kurabayashii?
• Trillium lancifolium?
• Trillium ludovicianum?
• Trillium luteum?
• Trillium maculatum?
• Trillium oestingii?
• Trillium parviflorum?
• Trillium petiolatum?
• Trillium recurvatum? - Prairie Trillium
• Trillium reliquum? - Relict Trillium
• Trillium sessile? - THE "Sessile Trillium"
• Trillium staminium?
• Trillium underwoodii?
• Trillium viride?
• Trillium viridescens?

Some Hybrid Trilliums in the Wild

"Susquehanna" Trilliums

Trillium diseases

Several species of pedicillate Trilliums are known to to be infected with a mycoplasma which causes petal and leaf distortions and often green stripes and splotches on the petals. This has been most often observed on Trillium grandiflorum. In the past these plants with green on the petals were often sold for high prices as rare cultivars before it was recognized as a symptom of a disease. The mycoplasma infected plants usually grow poorly and die. There are a few reports of T. grandiflorum and T.erectum plants with green on the petals which are very healthy and long-lived. It is not known whether or not these are resistant mycoplasmal infected plants or a genetic mutation with green petal as have been occasionally found in many other plants and brought into cultivation. (See "Trilliums" by Case and Case, 1997 for more information.)

A Potyvirus has been reported to infect nearly all species of Trillium being grown in a collection in the UK. The plants become distorted and dwindle and die in a year or two.

Both these diseases are probably transmitted by sucking insects like aphids and leafhoppers.

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