Trillium erectum
Trillium parviflorum
birthwort, red trillium, red wakerobin, stinking Benjamin, stinking willie, wake-robin
small-flower trillium
short, thick, praemorse.
horizontal to ± erect, brownish, thick, praemorse, not brittle.
1–2, often with numerous offsets forming heavy clumps, round in cross section, 1.5–6 dm, ± robust, glabrous.
1–3, round in cross section, 1.7–3 dm, slender to robust, glabrous.
sessile;
blade bright green, lacking dark pigmentation, major veins prominent, broadly rhombic to ovate-rhombic, 5–20 × 5–20 cm, about as broad as long, widest near middle, base attenuate, apex acuminate.
held well above ground, sessile;
blade green with widely scattered mottling, mottling becoming obscure with age, ovate to broadly ovate, 6.5–16 × 5–8 cm, not glossy, apex obtuse.
erect, ascending, or proximal to but above bracts, odor fetid, like a wet dog;
perianth open, flat;
sepals flat to sulcate apically, green, often streaked or overlain with maroon, occasionally entirely dark maroon, lanceolate-acuminate, 10–50 mm, equaling petals, ± 1/2 petal width, texture leafy, margins entire, apex acuminate;
petals spreading, carried in same plane as sepals or ascending slightly, dark reddish brown, maroon, purple, or white, sometimes pale yellow, major adaxial veins prominent and appearing somewhat engraved, usually flat, lanceolate, ovate-lanceolate, or occasionally ovate, 1.5–5 × 1–3 cm, 2 times sepal width, widest near base, heavy-textured, apex acuminate;
stamens erect to slightly recurved, 5–15 mm;
filaments white, pinkish, or dark purple, ± equaling anthers, but variable within local populations, thin;
anthers erect or weakly recurving, dark maroon, grayish maroon, or yellowish, strongly yellow when pollen exposed, 5–12 mm, dehiscence introrse;
ovary dark purple to maroon, even in white-flowered forms, ovoid, elliptic to globose, 6-angled, angles forming very low ridges when fruit is ripe, 5–10 mm, broadly attached at base;
stigmas recurved, distinct, dark purple, not lobed adaxially, subulate, short, 3–7 mm, ca. 1/2 or less length of ovary at anthesis, fleshy;
pedicel straight, erect, or somewhat declined but not strongly recurved below bracts, 1–10+ cm.
erect, odor spicy, of cloves;
sepals displayed above bracts, spreading, divergent, green, lanceolate, 16–25 × 4–8 mm, margins entire, flat, apex variously obtuse to rounded;
petals long-lasting, erect to erect-spreading, ± connivent, ± concealing stamens and ovary, white, occasionally purple stained basally, sometimes weakly spirally twisted, linear to linear-lanceolate, 2.2–4.5 × 0.4–1 cm, thin-textured, base occasionally cuneate, margins entire, apex obtuse;
stamens erect, 10–15.5 mm;
filaments white, greenish white, or purple stained, 1–3 mm, much shorter than anthers, slender;
anthers erect, straight, greenish white, 9–11+ mm, ± slender, dehiscence latrorse;
connective greenish, straight, barely extended (to 0.4 mm) beyond anther sacs;
ovary green or green and purple basally, ovoid, obscurely 6-gonal, 4–8 mm;
stigmas erect, ± divergent, distinct, green, outer surface purple, subulate, 3–4.5 mm, ± fleshy, thickened.
dark maroon, weakly fragrant of fruit, ± globose to slightly pyramidal, 1–1.6 × 1–1.5 cm, juicy.
dark reddish purple or maroon, fragrance not reported, subglobose, ± 1 cm, ± juicy.
= 10.
= 10.
Trillium erectum
Trillium parviflorum
Varieties 2 (2 in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Trillium parviflorum varies from very short, slender, small-bracted plants to tall, broad, umbrella-bracted giants. Regardless of plant or bract sizes, flower and petal sizes are remarkably constant, all plants having small, linear-lanceolate petals. This is not usually the case with T. albidum, the species with which this plant is most likely to be confused. In T. albidum also the plants can be enormous, but when they are, the petals are very long, broad, and conspicuously obovate-diamond-shaped. In large clonal clumps of T. albidum, the larger and more mature offsets show the typical petal shape, while the smaller and presumably youngest offsets sometimes produce smaller, narrower petals, more like those of T. parviflorum.
Some western botanists, more experienced with local populations than I, do not consider Trillium parviflorum to be distinct from T. albidum. They point out that since there is an extensive region of apparent intergradation (as indeed there is, well supported by herbarium vouchers), there exists a morphological cline from the long- and wide-petaled T. albidum to the narrower- and generally shorter-petaled T. parviflorum, and that T. parviflorum, therefore, should not be considered a separate species but rather a subspecies or a variety. Since no one to date has treated T. parviflorum at the subspecific or varietal level, and since in my own limited experience it does appear as a distinct species in Washington north of the Columbia River, I include it here as treated by Soukup. I have seen populations of considerable variation north of Corvallis, Oregon, and agree that there is much overlap with T. albidum. Obviously there is need for a much more extensive study of this situation.
A factor that exacerbates this problem (and many others in Trillium), is that nutrition, age, and even favorable position in the habitat can greatly influence plant and floral organ sizes. In many species, including T. albidum, when a single vigorous clonal clump produces many offsets, the oldest offsets may have flowers with very large petals, sepals, ovary, etc., while the younger offsets may have organs only half the size. In most sessile trilliums particularly, population averages are often more useful than isolated individual measurements, a difficult situation, indeed.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Petals usually red, maroon, or dark purple. | var. erectum |
1. Petals white. | var. album |
WildflowerSearch
iNaturalist
USDA Plants Database
OR
Flora NW
PNW Herbaria
