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

giant purple wakerobin, narrow petal wakerobin, narrow-petal trillium

Habit Plants tall, very robust.
Rhizomes

horizontal, brownish, thick, praemorse, fleshy.

erect, brownish, thick, somewhat compressed-thickened, praemorse, not brittle.

Scapes

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

1–2, round in cross section, 2.5–6 dm.

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).

held well above ground, spreading horizontally, subsessile;

blade very sparsely mottled with dark greenish brown or rarely all green, mottling becoming obscure with age, broadly ovate, 10–22 × 8.7–15 cm, not glossy, often narrowed to falsely petiolate, very short, and narrowly cuneate base 10–20 mm, apex obtuse.

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.

erect, odor spicy-musty, musty, or fetid;

sepals conspicuous, spreading, often resting on bracts, maroon to green, linear to oblong-lanceolate, 35–47 × 8–10 mm, margins flat, entire, apex acute;

petals long-lasting, erect, ± connivent, ± concealing stamens and ovary and partially obscuring stamens, dark purple to red-purple, not spirally twisted, veins obscure, linear, 5–10 × 0.7–1.4 cm, 8–10 times longer than wide, glossy, thick-textured, base linear, margins entire, at first flat but inrolling with age, apex variously acute-obtuse;

stamens erect, 12–22 mm;

filaments dark maroon, 2–4 mm, slender, widest at base;

anthers erect, straight, purple, 12–18 mm, dehiscence introrse;

connectives purple, slightly extended 1–1.5 mm beyond anther sacs;

ovary dark, ovoid-ellipsoid, 6-angled toward apex, 7.5–12 mm;

stigmas erect, divergent-recurved, distinct, purple, sessile, awl-shaped, thickly subulate, 5 mm, thick, fleshy.

Fruits

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

dark purple, fragrance unknown, subglobose, 6-angled, almost winged, fleshy.

2n

= 10.

= 10.

Trillium sessile

Trillium angustipetalum

Phenology Flowering spring (Mar–early May). Flowering spring–early summer (Mar–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 Big-tree (Sequoiadendron) groves and other mixed coniferous-deciduous flatwoods, slightly damper depressions under maples and deciduous shrubs, coastal mountains, oak (Quercus) groves in ravines and otherwise quite arid, almost treeless chaparral, wooded canyon slopes, dense woods near streams
Elevation 100–300 m (300–1000 ft) 30–200 m (100–700 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
CA
[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.)

Trillium angustipetalum occurs in the Sierra Nevada from Fresno County north to Placer County (J. D. Freeman 1975). It is disjunct in the coastal mountains and hills of Santa Barbara and San Luis Obispo counties.

B. D. Ness (1993) listed Trillium kurabayashii as a synonym of T. angustipetalum. In bract orientation, color, and texture, and in petal shape, the two are quite different and certainly not the same species. Cytologist Masataka Kurabayashi found chromosomal differences between the two species (reported by J. D. Freeman 1975).

(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. Phyllantherum
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. 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. sessile, T. simile, T. stamineum, T. sulcatum, T. underwoodii, T. undulatum, T. vaseyi, T. viride, T. viridescens
Synonyms T. sessile var. angustipetalum, T. giganteum var. angustipetalum
Name authority Linnaeus: Sp. Pl. 1: 340. (1753) (Torrey) J. D. Freeman: Brittonia 27: 55. (1975)
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