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Published In: Species Plantarum 1: 339. 1753. (1 May 1753) (Sp. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library

Project Name Data (Last Modified On 7/9/2009)
Acceptance : Accepted
Project Data     (Last Modified On 7/22/2009)


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23. Trillium L. (trillium, wake robin)

(Case and Case, 1997)

Plants perennial, with usually short rhizomes, lacking the odor of onion or garlic. Aerial stems unbranched below the inflorescence, erect or nearly so, glabrous or sometimes slightly scabrous. Leaves a single whorl of 3 (4 or 5 in aberrant plants) at the tip of the aerial stem, narrowly to broadly ovate or elliptic, glabrous (sometimes with minute, hairlike, scabrous outgrowths near the base along the undersurface veins). Inflorescences of a single flower at the tip of the aerial stem. Flowers sessile or stalked, not subtended by bracts, none of them replaced by bulblets. Perianth with the sepals and petals free, the sepals herbaceous and green, sometimes reddish tinged, the petals white, pink, maroon, brick red, or greenish yellow, rarely yellow or green. Stamens 6, free, erect. Styles 3, the bases erect and sometimes fused, the upper portions elongate, spreading, the stigmatic areas along the inner sides. Ovary superior, with 3 locules, each with 4–10 ovules, 3- or 6-angled, ribbed or winged. Fruits berries, 8–25 mm long, ovoid to ellipsoid, the tips beaked with the persistent styles. About 50 species, North America, Asia.

Some species of Trillium were used historically in herbal medicine, but the most common use of the genus is as ornamentals in the shade garden. The species are relatively difficult to grow from seed; plants must be several years old before they will flower. Consequently, many of the plants sold at nurseries have been excavated from natural populations by unscrupulous collectors. This has adversely affected several of the species and the habitats in which they grow. Because of this and because many such plants were excavated without proper care and will not survive transplantation, gardeners are urged to become aware of the sources for their plants and to insist on nursery-propagated plants grown from seeds or rhizome divisions of cultivated stocks.


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1 Flowers sessile (2)
+ Flowers stalked (5)
2 (1) Sepals reflexed from the base and pointing downward at flowering; leaves narrowed to a short petiole 4 Trillium recurvatum
+ Sepals spreading to ascending at flowering; leaves sessile (3)
3 (2) Petals 15–36 mm long, lanceolate to narrowly elliptic, broadest at or below the middle, narrowed at the base but the stalklike portion absent or less than 2 mm long; stamens half or more than half as long as the petals 5 Trillium sessile
+ Petals (36–)40–75 mm long, oblanceolate to nearly linear, broadest above the middle, narrowed to a stalklike base 7–15 mm long; stamens less than half as long as the petals (4)
4 (3) Leaves with blunt to broadly pointed tips, often somewhat mottled, the upper surface with numerous stomates (appearing as tiny, white speckles under magnification) 6 Trillium viride
+ Leaves with sharp-pointed to somewhat acuminate tips, usually not mottled, the upper surface lacking stomates or with only a few near the tip 7 Trillium viridescens
5 (1) Leaves 7–20 cm long, about as long as wide, strongly acuminate at the tip; flowers spreading horizontally to nodding below the leaves at flowering, the stalks 3–12 cm long 1 Trillium flexipes
+ Leaves 1.5–7(–9) cm long, 2 or more times longer than wide, often pointed, but not acuminate at the tip; flowers erect or ascending above the leaves at flowering (sometimes nodding in fruit), the flower stalks 1–3 cm long (6)
6 (5) Leaves with a petiole 5–10 mm long; aerial stems 3–10(–15) cm long; fruits nodding below the leaves 2 Trillium nivale
+ Leaves sessile; aerial stems 10–30 cm long; fruits erect or ascending, above the leaves 3 Trillium pusillum
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