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giant trillium, giant white wakerobin, sessile trillium, smallflower trillium, white toadshade

brook trillium, brook wake-robin

Rhizomes

horizontal, ± erect, brown, superficially bulblike, short, thick, not brittle.

horizontal, short, praemorse, fleshy.

Scapes

often several from same rhizome terminus, round in cross section, 2.2–5.8 dm, stout.

1–2, round in cross section, 0.4–1.5 dm, slender, glabrous.

Bracts

held well above ground, sessile;

blade weakly mottled with scattered, darker green spots, mottling often fading later in season, broadly ovate, 10–20 × 12–15 cm, not glossy, base rounded, apex obtuse.

distinctly petiolate;

blade bluish green, occasionally with silvery green pattern along major veins, ovate-lanceolate, 1.5–8 × 0.8–6 cm, somewhat thick-textured, glossy, weakly to strongly cordate basally, apex long-acuminate;

petiole (0.5–)1–3(–6) cm.

Flower

borne directly upon bracts, erect, fragrance roselike;

sepals conspicuous, spreading, displayed above bracts, pale green, lanceolate, 30–65 × 12–15 mm, margins entire, apex acute;

petals long-lasting, usually erect or slightly spreading, ± connivent, ± concealing stamens and ovary basally, white to creamy white, rarely soft pinkish rose near base, veins prominent but not engraved, not spirally twisted, obovate, more lanceolate in young plants, 4.8–8 × 2.2–3 cm, widest at or just above middle, ± thick-textured, base cuneate, margins entire, ± flat, apex rounded to acute;

stamens erect, greenish white, 15–25 mm;

filaments whitish green, 3–4 mm, slender;

anthers erect, straight, yellow, 11–20 mm, dehiscence latrorse;

connectives straight, extended ca. 1 mm beyond anther sacs, rounded;

ovary green or occasionally purple, ovoid, rounded 6-gonal, 6–11 mm;

stigmas erect to spreading, distinct, sessile, subulate, 4–7 mm, thin distally.

erect, rapidly recurving below bracts after pollination, ± odorless;

sepals conspicuous, spreading, green, weakly sulcate, oblong or tapered apically, usually shorter and narrower than petals, 10–23 × 4–8 mm, margins entire, apex rounded-apiculate;

petals erect-spreading, not recurved or only in distal 1/2, white (rarely pale pink), usually with dark madder-purple flecks, rarely almost entirely covered with madder-purple, color not changing with age, veins inconspicuous, not engraved, ovate-cordate to ± orbicular, tapered bluntly apically above middle, 1.3–2.8 × 1–2.4 cm, ± thin-textured, base rounded, cuneate, margins entire, mostly without undulations, apex ± apiculate-acuminate;

stamens erect, 5–12 mm;

filaments white, ± equaling anthers;

anthers straight, yellow, 3–6 mm, dehiscence ± extrorse;

connectives not extended beyond anther sacs;

ovary creamy white, ovoid, weakly 6-angled but angles in close pairs, giving superficial impression of 3-angled ovary, short, 3–9 × 4 mm, somewhat obscured by anthers broadly attached;

stigmas recurved and appearing ± lobed adaxially, at least in dried specimens, connate basally to distinct and closely grouped, white or cream, 2–4 mm, uniformly thick, fleshy;

pedicel strongly erect at anthesis, strongly recurving and elongating below bracts after pollination, 2.5–11 cm.

Fruits

green or purplish green, fragrance unknown, ovoid to globose, pulpy, juicy.

greenish white, odorless, globose, 0.9–1.2 × 0.8–1 cm, pulpy, not juicy.

2n

= 10.

Trillium albidum

Trillium rivale

Phenology Flowering spring (mid Mar–late Apr). Flowering spring (early Mar–early Jun); withering in summer.
Habitat Moist slopes in rich mixed deciduous-coniferous forests or coniferous stands, brushy thickets on flats, open fields, pastures, and fencerows, dense second-growth coniferous forests, floodplains along streams and larger rivers Open, grassy hillsides, manzanita shrubbery, pine groves, clearings in sequoia groves, roadside banks, ledges, gravelly talus
Elevation 100–200 m (300–700 ft) 10–1400 m (0–4600 ft)
Distribution
from FNA
CA; OR
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; OR
[WildflowerSearch map]
Discussion

Trillium rivale is confined to the Klamath and Siskiyou mountains of southwestern Oregon and California. It has a strong affinity for banks along streams and adjacent to trickles in Darlingtonia bogs, mainly on serpentine soils. After flowering, the entire plant may enlarge and become more robust and turgid with very glossy leaves.

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

Source FNA vol. 26, p. 106. FNA vol. 26, p. 102.
Parent taxa Liliaceae > Trillium > subg. Phyllantherum Liliaceae > Trillium > subg. Trillium
Sibling taxa
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. 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. nivale, T. ovatum, T. parviflorum, T. persistens, T. petiolatum, T. pusillum, T. recurvatum, T. reliquum, T. rugelii, T. sessile, T. simile, T. stamineum, T. sulcatum, T. underwoodii, T. undulatum, T. vaseyi, T. viride, T. viridescens
Name authority J. D. Freeman: Brittonia 27: 48, fig. 11. (1975) S. Watson: Proc. Amer. Acad. Arts 20: 378. (1885)
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