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Trillium ovatum

Pacific trillium, trillium, western trillium, western wake-robin, western white trillium, white or western trillium, white trillium

dwarf white trillium, snow trillium, snow wakerobin

Rhizomes

semierect to horizontal, short, stout, praemorse.

short, praemorse.

Scapes

1–2, round, 2–5 dm, ± slender, glabrous.

usually 1, 6-gonal in cross section, 0.3–0.5 dm at onset of anthesis, expanding to 0.45–0.8 dm, slender, glabrous.

Bracts

sessile, subsessile, or short-petiolate;

blade medium green, sometimes blotched and mottled, main veins prominent, ovate-rhombic, 7–12 × 5–20 cm, continuing to expand during anthesis, base rounded, apex acuminate.

distinctly petiolate;

blade bluish green, elliptic-ovate to ovate, 1.5–4.5 cm × 0.7–34 mm, base abruptly rounded to petiole, apex round-obtuse.

Flower

erect or nodding, odorless;

sepals spreading to horizontal, green, lanceolate to oblong-lanceolate, 15–50 × 6–20 mm, margins entire, apex acute;

petals erect-ascending, usually wide-spreading from base, exposing entire pistil, white or with pink or blush markings, lacking V-shaped markings, fading to rosy pink, purple, or dark red, veins not deeply engraved, ± linear to widely obovate, 1.5–7 ×1–4 cm, widest at or above middle, thin-textured, margins flat to undulate, apex acuminate;

stamens prominent, slightly recurved-spreading to straight, 10–18 mm;

filaments white, shorter than anthers, slender;

anthers yellow, 4–16 mm, slender, dehiscence latrorse-introrse;

ovary green or white, ovoid, 6-angled, 5–12 mm, attachment ± 3/4 ovary width;

stigmas recurved, barely connate basally, greenish white or white, linear, not lobed adaxially, 6–10 mm, uniformly thin;

pedicel erect to leaning, 2–6 cm.

erect, fragrance sweet;

sepals spreading, flat, bluish green, lanceolate, 10–32 × 2–7 mm, shorter than petals, margins entire, apex obtuse;

petals very showy, recurved to erect-spreading, white, veins not engraved on adaxial surface, ovate-elliptic to oblong, 1.5–3.5+ × 0.8–1.5 cm, thin- to firm-textured, margins entire to slightly wavy, apex obtuse-acuminate;

stamens straight, 5–18 mm;

filaments white, slightly shorter than anthers, slender;

anthers straight, pale yellow, 2.5–11 mm, thin, dehiscence introrse;

ovary greenish white, ± globular, obtusely 3-angled;

style with tips spreading, elongate, 0.5–1.5 mm, slender;

stigmas prominent, recurved or curled, connate basally, white, linear, threadlike, 4–12+ mm;

pedicel erect in anthesis, rapidly recurving below leaves after pollination, 5–20 cm.

Fruits

baccate, green or white, ± odorless, broadly ovoid, obscurely winged, 1.2–2.8 × 0.7–1.9 cm, pulpy-moist.

greenish white, odorless, globose-ovate, 0.6–1 × 0.5–0.8 cm, pulpy, not juicy.

2n

= 10.

= 10.

Trillium ovatum

Trillium nivale

Phenology Flowering spring (early Mar–early Apr).
Habitat Forested, limestone-derived soils, alkaline glacial drift or loess, creeping soils at head of ledges, talus of cliff bases, crevices in limestone cliffs, gravelly deposits on higher floodplain riverbanks
Elevation 100–300 m (300–1000 ft)
Distribution
from USDA
w North America
[WildflowerSearch map]
[BONAP county map]
from FNA
IA; IL; IN; KY; MD; MI; MN; MO; NE; OH; PA; SD; WI; WV
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 2 (2 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Trillium nivale occurs primarily at the southern edge of Pleistocene glaciation and shuns humus, leaf deposits, and much plant competition.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Bracts sessile; petals lanceolate to obovate, 1.5–7 × 1–4 cm
var. ovatum
1. Bracts distinctly short-petiolate; petals linear to linear-lanceolate, 0.5–2.4 × 0.2–0.6 cm
var. oettingeri
Source FNA vol. 26, p. 100. FNA vol. 26, p. 100.
Parent taxa Liliaceae > Trillium > subg. Trillium Liliaceae > Trillium > subg. Trillium
Sibling taxa
T. albidum, T. angustipetalum, T. catesbaei, T. cernuum, T. chloropetalum, T. cuneatum, T. decipiens, T. decumbens, T. discolor, T. erectum, T. flexipes, T. foetidissimum, T. gracile, T. grandiflorum, T. kurabayashii, T. lancifolium, T. ludovicianum, T. luteum, T. maculatum, T. nivale, T. parviflorum, T. persistens, T. petiolatum, T. pusillum, T. recurvatum, T. reliquum, T. rivale, T. rugelii, T. sessile, T. simile, T. stamineum, T. sulcatum, T. underwoodii, T. undulatum, T. vaseyi, T. viride, T. viridescens
T. albidum, T. angustipetalum, T. catesbaei, T. cernuum, T. chloropetalum, T. cuneatum, T. decipiens, T. decumbens, T. discolor, T. erectum, T. flexipes, T. foetidissimum, T. gracile, T. grandiflorum, T. kurabayashii, T. lancifolium, T. ludovicianum, T. luteum, T. maculatum, T. ovatum, T. parviflorum, T. persistens, T. petiolatum, T. pusillum, T. recurvatum, T. reliquum, T. rivale, T. rugelii, T. sessile, T. simile, T. stamineum, T. sulcatum, T. underwoodii, T. undulatum, T. vaseyi, T. viride, T. viridescens
Subordinate taxa
T. ovatum var. oettingeri, T. ovatum var. ovatum
Name authority Pursh: Fl. Amer. Sept. 1: 245. (1814) Riddell: Syn. Fl. West. States, 93. (1835)
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