We must admit that we have no idea what this plant is doing here. We had first identified this as Trillium sessile, but Mr. Scott Namestnik pointed out in a comment that this plant clearly seems to be T. recurvatum. But how did it get here in Bird Park, Mount Lebanon, merrily blooming in mid-May as if it were perfectly at home? Neither Gray nor the USDA PLANTS database places any wild populations of Trillium recurvatum anywhere in the Pittsburgh metropolitan area, or even within two hundred miles. It is a prairie-state plant, almost unknown in Ohio, and not common till Indiana, although (oddly) there is apparently an isolated wild population way over in Lancaster County, Pennsylvania. Is someone attempting to populate Bird Park with unusual wildflowers? Or have we discovered something previously unknown in the botanical literature—another isolated wild population, like the one in Lancaster County?

Gray describes the genus and the species:

TRÍLLIUM L. WAKE ROBIN. BIRTHROOT. Sepals 3, lanceolate, spreading, herbaceous, persistent. Petals 3, larger, withering in age. Stamens б; anthers linear, on short filaments, adnate. Styles awl-shaped or slender, spreading or recurved above, persistent, etig matic down the inner side. Seeds ovate, horizontal, several in each cell. — Low perennial herbs, with a stout and simple stem rising from a short and praemorse tuber-like rootstock, bearing at the summit a whorl of 3 ample, commonly broadly ovate, more or less ribbed but netted-veined leaves, and a terminal large flower; in spring. (Name from tres, three; all the parts being in threes.) — Monstrosities are not rare with the calyx and sometimes petals changed to leaves, or the parts of the flower increased in number.

Ovary and fruit 6-angled and more or less winged.

Flower sessile; leaves usually mottled.

T. recurvàtum Beck. Leaves contracted at the base into a petiole, ovate, oblong, or obovate; sepals reflexed; petals pointed, the base narrowed into a claw, oblong-lanceolate to -ovate, dark purple; fruit ovoid, strongly winged above, 1.8 cm. long. — Rich woods, O. to Minn., Ark., “Miss.,” and Tenn.

Two early bloomers among the Trilliums in Bird Park, Mount Lebanon, where they were beginning to bloom in late April. This species is most commonly mahogany red in most of its range, but in our area the white form (more pictures here and here) is most common. There is also a pink form and a greenish-yellow form.

Gray describes the genus and the species:

TRÍLLIUM L. WAKE ROBIN. BIRTHROOT. Sepals 3, lanceolate, spreading, herbaceous, persistent. Petals 3, larger, withering in age. Stamens б; anthers linear, on short filaments, adnate. Styles awl-shaped or slender, spreading or recurved above, persistent, stigmatic down the inner side. Seeds ovate, horizontal, several in each cell. — Low perennial herbs, with a stout and simple stem rising from a short and praemorse tuber-like rootstock, bearing at the summit a whorl of 3 ample, commonly broadly ovate, more or less ribbed but netted-veined leaves, and a terminal large flower; in spring. (Name from tree, three; all the parts being in threes.) — Monstrosities are not rare with the calyx and sometimes petals changed to leaves, or the parts of the flower increased in number.

Ovary and fruit 6-angled and more or less winged.

Flower pediceled; connective narrow, not produced; leaves subsessile.

Anthers at anthesis exceeding the stigmas.

T. eréctum L. Leaves very broadly rhombic, shortly acuminate ; peduncle (2—8 cm. long) usually more or less inclined or declínate; petals ovate to lanceolate (18-36 mm. long), brown-purple or often white or greenish or pinkish; stamens exceeding the stout distinct spreading or recurved stigmas; ovary purple; fruit ovoid, 2.5 cm. long, reddish. — Rich woods, e. Que. to Ont., southw. to Pa. and in the mts, to N. C. — Flowers ill-scented.

The ordinary color of this flower is deep mahogany red, but in the Squaw Run valley the flowers are almost always white. Occasionally a pink one shows up, as this one did, which was blooming at the beginning of May.

The odor  is described in the Flora of North America as “like a wet dog,” which is unmistakable, and accounts for another common name, Stinking Willie. It’s not a flower to sniff with delight.

Gray describes the genus and the species:

TRÍLLIUM L. WAKE ROBIN. BIRTHROOT. Sepals 3, lanceolate, spreading, herbaceous, persistent. Petals 3, larger, withering in age. Stamens б; anthers linear, on short filaments, adnate. Styles awl-shaped or slender, spreading or recurved above, persistent, stigmatic down the inner side. Seeds ovate, horizontal, several in each cell. — Low perennial herbs, with a stout and simple stem rising from a short and praemorse tuber-like rootstock, bearing at the summit a whorl of 3 ample, commonly broadly ovate, more or less ribbed but netted-veined leaves, and a terminal large flower; in spring. (Name from tree, three; all the parts being in threes.) — Monstrosities are not rare with the calyx and sometimes petals changed to leaves, or the parts of the flower increased in number.

Ovary and fruit 6-angled and more or less winged.

Flower pediceled; connective narrow, not produced; leaves subsessile.

Anthers at anthesis exceeding the stigmas.

T. eréctum L. Leaves very broadly rhombic, shortly acuminate; peduncle (2—8 cm. long) usually more or less inclined or declínate; petals ovate to lanceolate (18-36 mm. long), brown-purple or often white or greenish or pinkish; stamens exceeding the stout distinct spreading or recurved stigmas; ovary purple; fruit ovoid, 2.5 cm. long, reddish. — Rich woods, e. Que. to Ont., southw. to Pa. and in the mts, to N. C. — Flowers ill-scented.

The Great White Trillium loves to grow in vast colonies. It’s not all that common, but when you do find a stand of them, it may cover acres, as it does here along the aptly named Trillium Trail in Fox Chapel, where these plants were all blooming at the end of April.

Sometimes a flower takes on a pink flush as it ages, as you see in two of the examples here.

Gray describes the genus and the species:

TRÍLLIUM L. WAKE ROBIN. BIRTHROOT. Sepals 3, lanceolate, spreading, herbaceous, persistent. Petals 3, larger, withering in age. Stamens б; anthers linear, on short filaments, adnate. Styles awl-shaped or slender, spreading or recurved above, persistent, stigmatic down the inner side. Seeds ovate, horizontal, several in each cell. — Low perennial herbs, with a stout and simple stem rising from a short and praemorse tuber-like rootstock, bearing at the summit a whorl of 3 ample, commonly broadly ovate, more or less ribbed but netted-veined leaves, and a terminal large flower; in spring. (Name from tree, three; all the parts being in threes.) — Monstrosities are not rare with the calyx and sometimes petals changed to leaves, or the parts of the flower increased in number.

T. grandiflorum (Michx.) Salisb. Leaves less broadly rhombic-ovate; pedicel erect or ascending; petals oblanceolate, often broadly so (4-6 cm. long), white turning rose-color or marked with green; stamens with stout filaments (persistently green about the fruit) and anthers, exceeding the very slender erect or suberect and somewhat coherent stigmas; fruit subglobose. Rich woods, w. Que. and w. Vt. to Minn., Mo., and N. C.

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In Wild Flowers Every Child Should Know, Frederic William Stack gives us this description:

LARGE FLOWERED WAKE-ROBIN

Trillium grandiflbrum. Lily Family.

The Trilliums rank among the foremost of our native woodland wild flowers, and they possess an individuality that compares favourably with the exclusive traits of the Arbutus, the Gentians, the Lobelias, and the Orchids. This beautiful, large, white-flowered species is one of the choicest and best known of its family. It is found during May and June, in damp, rich woods, and grows from eight to eighteen inches high. The single, smooth, stout, juicy stalk terminates with a whorl of three large, handsome, broadly egg-shaped, triple-ribbed leaves which taper suddenly at the apex and are narrowed to a stemless base. They are loose-textured, prominently veined, and toothless. The large, waxy-white, solitary flower is borne on a short stem that springs upright from the centre of the leaves. The three thin, broad, strongly veined, and long-pointed petals are larger and much longer than the three spreading, green, lanceshaped sepals, and they turn outward with a large graceful curve. They are scentless, and as they age they become pink. The single berry is nearly black when matured. This showy-flowered Trillium ranges from Canada to Florida, and west to Minnesota and Missouri.