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sessile trillium, sessile-flower wake-robin, toad trillium, toadshade

great white trillium, large-flower trillium, trille grandiflore, white trillium, white wake-robin

Rhizomes

horizontal, brownish, thick, praemorse, fleshy.

short, thick, praemorse.

Scapes

1–3, round in cross section, 0.8–2.5 dm, slender to stout, glabrous.

(1–)2–3(–many), round in cross section, 1.5–3+ dm, thick, glabrous.

Bracts

held well above ground, sessile;

blade green to bluish green, strongly to sparsely mottled, mottling becoming obscure with age, oval to suborbicular, 4–10 × 2–8 cm, base broadly attached, apex rounded-acuminate to bluntly parallel sided-acuminate (rounded basally to its broad attachment).

sessile or subsessile (occasionally weakly cuneate basally);

blade dark green with maroon overtones early, ovate-rhombic, 12–20 × 8–15 cm, apex acuminate.

Flower

erect, odor pungent, spicy;

sepals displayed above bracts, spreading, green, variously streaked with maroon, lanceolate-oblanceolate, 9–35 × 4–8 mm, margins entire, apex rounded-acuminate;

petals long-lasting, erect, ± connivent, ± concealing stamens and ovary, maroon, brownish maroon, green, or yellowish green, not spirally twisted, oblanceolate to elliptic, occasionally almost orbicular, 1.7–3.5 × 0.7–2 cm, thick-textured, narrowed near basal attachment (but not truly clawed), margins entire, apex gradually rounded-tapered to acute;

stamens straight, 10–23 mm;

filaments red-purple, 2–5 mm, dilated basally;

anthers erect, straight, gray-purple, 9–16 mm, thick, dehiscence introrse;

connectives purplish brown, straight, projecting 2–5+ mm beyond anther sacs;

ovary greenish white basally, purple distally, ovoid to globose, 6-angled, pyramidally narrowed to stigmas, 4–8.5 mm;

stigmas erect, divergent-recurved, distinct, purple, subulate, 1–5 mm, ± fleshy.

outfacing, erect, odorless;

sepals spreading, flat, green, very rarely streaked with maroon-purple, lanceolate, 20–55 × 12–23 mm, margins entire, apex acuminate or acute;

petals erect basally, recurving somewhat above middle to produce strongly funnelform corolla, obscuring ovary and base of style, white or rarely pink, without V-shaped or other markings, fading to dull pinkish purple, veins of adaxial surface conspicuous but not appearing engraved, shape variable, lanceolate to oblong, obovate, or, rarely, suborbicular, sides often parallel, 4–7.5 × 2–4 cm, thin-textured, base abruptly attenuate, margins overlapping basally, rolled, undulate-wavy in distal 1/2, apex ± acuminate;

stamens straight or barely recurved, 9–27 mm;

filaments white, much shorter than anthers, relatively thin;

anthers recurving slightly, pale yellow, strongly yellow when pollen exposed, long, 5–16 mm, slender, dehiscence introrse;

ovary inconspicuous, pale green or white, ovoid, 6-angled, 8–18 mm, basal attachment narrower than ovary width;

style barely united for 0.5–2 mm or merely closely grouped and separate;

stigmas erect, becoming spreading, weakly connate basally, pale green-white, uniformly linear, 3–18 mm, equaling or exceeding ovary, slender;

pedicel erect-ascending to strongly erect, 2–8+ cm.

Fruits

baccate, dark greenish purple, odorless, subglobose, 6-angled, angles somewhat winglike, pulpy, not juicy.

pale green, odorless, ± globose, obscurely 6-angled, 1.2–1.6 × 0.8–1.4 cm, mealy, moist (not juicy).

2n

= 10.

= 10.

Trillium sessile

Trillium grandiflorum

Phenology Flowering spring (Mar–early May). Late spring–early summer (Apr–Jun).
Habitat Rich woodlands, limestone districts, calcareous soils, floodplains, riverbanks, clayey alluvium, less fertile soils, high, dry limestone woods, persists under light pasturing, in fencerows and brushy areas after lumbering Rich deciduous or mixed coniferous-deciduous upland woods, floodplains, roadsides
Elevation 100–300 m (300–1000 ft) 20–700 m (100–2300 ft)
Distribution
from FNA
AL; AR; IL; IN; KS; KY; MD; MI; MO; NC; NY; OH; OK; PA; TN; VA; WV
[WildflowerSearch map]
[BONAP county map]
from FNA
CT; DE; GA; IA; IL; IN; KY; MA; MD; ME; MI; MN; NC; NH; NJ; NY; OH; PA; SC; TN; VA; VT; WI; WV; NS; ON; QC
[WildflowerSearch map]
[BONAP county map]
Discussion

Trillium sessile is rather uniform throughout its range, with few color forms.

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

Most variants of Trillium grandiflorum have green stripes or markings on the petals, many with numerous (4–30+) extra petals and/or bracts, and, often, much-deformed, monstrous characteristics. G. R. Hooper et al. (1971) showed that mycoplasmic organisms were present in all such forms examined, and were absent from normal plants. Most such forms should not be named taxonomically but, unfortunately, many have been. Nearly all of those that I examined represented stages in the development of the mycoplasma infection. Trillium grandiflorum, unlike most trilliums, produces many-petaled “double” forms. Forma roseum Farwell, opening a striking clear salmon-pink, occurs very rarely throughout the range, but is frequent in mixed or pure colonies along the Blue Ridge Mountains of Virginia.

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

Source FNA vol. 26, p. 115. FNA vol. 26.
Parent taxa Liliaceae > Trillium > subg. Phyllantherum 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. ovatum, T. parviflorum, T. persistens, T. petiolatum, T. pusillum, T. recurvatum, T. reliquum, T. rivale, T. rugelii, 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. kurabayashii, T. lancifolium, T. ludovicianum, T. luteum, T. maculatum, T. nivale, 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
Synonyms T. rhomboideum var. grandiflorum, T. erythrocarpum
Name authority Linnaeus: Sp. Pl. 1: 340. (1753) (Michaux) Salisbury: Parad. Lond. 1: plate 1. (1805)
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