Wild Flowers of Pittsburgh


Evening Primrose (Oenothera Biennis)

A tall and stately weed whose flowers we almost never get to see in their full glory. It’s a night-bloomer, opening at dusk and fading in the early hours of the morning. These pictures were taken shortly after sunrise at the edge of a parking lot in Beechview, where Evening Primroses were blooming in the middle of August.

Flowers. Pale yellow; four broad petals; cross-shaped anther in the middle; borne in branching racemes.

Leaves. Lanceolate, sessile, slightly toothed; net-veined, with center rib often reddish toward base; alternate; thick on the stem, with branches or abortive branches in axils; mostly smooth.

Stem. Stout; somewhat sticky; woody below, with dark brownish stripes; to 6 feet or more; much branched.

At one time this plant was placed in a genus Onagra, from which the family Onagraceae was named; but Gray and most modern botanists make that genus part of Oenothera.

Gray describes the genus and the species:

OENOTHERA L. EVENING PRIMROSE. Calyx-tube prolonged beyond the ovary, deciduous; the lobes 4, reflexed. Petals 4. Stamens 8; anthers mostly linear and versatile. Capsule 4-valved, many-seeded. Seeds naked or with an obscure membranaceous crest. — Leaves alternate or rarely all basal. Flowers yellow, white, or rose-color. (An old name of unknown origin, for a species of Epilobium.)

§ 1. ONAGRA (Adans.) Ser. Stigma-lobes linear, elongated; flower-buds upright; petals yellow; fruit subcylindrical, elongated; seeds in 2 rotos in each cell; caulescent annuals or biennials.

O. biennis L. (COMMON E.) Rather stout, erect, 3-15 dm. high, usually simple, more or less spreading-pubescent to hirsute; leaves lanceolate to oblong or rarely ovate-lanceolate, repandly denticulate, acute or acuminate; bracts lanceolate, shorter than or scarcely exceeding the capsules; calyx-tube 2.5-3.5 cm. long; petals yellow, obovate, 1.5-2.5 cm. long; pods more or less hirsute, narrowed almost from the base, 2-3.5 cm. long. (Onagra Scop.) —Open places, common.


Purple-Leaved Willow-Herb (Epilobium coloratum)

The genus Empilobium includes some spectacular flowers, like Fireweed (E. angustifolium). It also includes these little weeds that you pass right by without noticing. They’re worth a look, though: up close the flowers are beautiful, and the plants often have purple stems or even purple leaves (in spite of the English name, purple leaves are by no means guaranteed) that add to the decorative effect. They like moist areas, and seem to have a special affinity in the city for damp sidewalks. The plant at right grew in the angle between a stone retaining wall and the sidewalk along a street in Beechview. The one below grew directly out of a crack in that same wall.

There are several similar species of Epilobium that have insignificant flowers like these, but this is the only one reported by Porter’s Flora of Pennsylvania and Shafer’s Preliminary List of the Vascular Flora of Allegheny County, Pennsylvania, as occurring in Allegheny County. “At best,” says Mathews (Field Book of American Wild Flowers), “the Epilobiums are a difficult genus to separate distinctly, and are not a little puzzling to the botanist.”

Gray describes the genus and the species:

EPILÒBIUM L. WILLOW-HERB. Calyx-tube scarcely or not at all prolonged beyond the ovary; limb 4-cleft or -divided. Petals 4, violet, magenta, pink, or white. Capsule slender, many-seeded. Seeds with a tuft of long hairs at the end. — Mostly perennial herbs with nearly sessile leaves. (Name from epi, on, and lobion, a little pod.)

E. coloràtum Muhl. Stem erect, not stoloniferous (often developing in late autumn sessile or subsessile basal rosettes), 3-9 dm. high, usually muchbranched, glabrous below, canescent at least in lines above with incurved hairs; leaves elongate-lanceolate, 6-16 cm. long, 1-2 cm. broad, distinctly short-petioled, closely and irregularly serrulate; flowers abundant on the divergent branches; petals pink, 3-5 mm. long; pedicels short; seed 1.6 mm. long, abruptly rounded at tip, minutely papillate; mature coma cinnamon-colored. — Low ground, Me. to Neb., and southw. July-Sept.

In The Species of Epilobium Occurring North of Mexico, William Trelease gives a fuller description, and points out the difficulty even botanists have in sorting out closely related species of Epilobium:

E. coloratum, Muhl. — Glabrate below, the rather numerous panicled branches canescent with incurved hairs at least along the decurrent lines, and more or less glandular towards the end; leaves 50 to 150 mm. long, lanceolate to oblong-lanceolate, acute, deeply and irregularly serrulate, mostly gradually narrowed to conspicuous slender petioles, glabrous except the uppermost, dull, thin, rugose-veiny; flowers very numerous, more or less nodding; petals 3 to 5 mm. long, rosy; fruiting peduncles slender, mostly short; seeds obconical-fusiform, beakless, strongly papillate, .3 x 1.5 mm.; coma at length cinnamon-colored, at least at base. — Willd. Enum. i. (1809), 411; Haussknecht, Monogr. 258; Barbey & Cuisin, pl. 9.—Wet ground and meadows, Canada to South Carolina, west to Wisconsin, Nebraska, and Missouri. — Specimens examined from Ontario, Maine, Massachusetts, Connecticut, New York, New Jersey, Pennsylvania, Virginia, South Carolina (Ravenel), West Virginia, Ohio, Illinois, Missouri, Kansas, Nebraska, Iowa, and Wisconsin.

This species, the general type of which is reproduced in a number of others which here follow it essentially in the order of their leaf and habit resemblance, differs from all of its congeners in the degree of serration of its leaves and especially in its elongated seeds destitute of the usual apical beak, and from all with which it is likely to be confounded, in the nearly cinnamon-colored ripe coma (which, however, is white in immature capsules that have dehisced while drying). It is apparently everywhere associated with E. adenocaulon, which begins to flower and fruit about a fortnight earlier, and differs in its very shortstalked leaves, rounded at base and less sharply toothed, and in its shorter seeds abruptly contracted and hyaline-beaked above, and with pure white coma. West American specimens which have been called E. coloratum belong, for the most part, to forms of adenocaulon.

Enchanter’s Nightshade (Circaea lutetiana)

A woodland plant with inconspicuous two-petaled flowers whose odd shape deserves a closer look, perhaps with a glass. This plant grew in a small, shady clearing in the woods in Mount Lebanon, where it was blooming in the middle of June.

Enchanter’s Nightshade has a longstanding reputation as a sorcerer’s plant, and indeed it may have been brought from Europe for that purpose. Modern magic-supply houses often sell the seeds.

Gray describes the genus and the species:

Calyx-tube slightly prolonged, the end filled by a cup-shaped disk, deciduous; lobes 2, reflexed. Fruit indehiscent, small and bur-like, bristly with hooked hairs, 1-2-celled; cells 1-seeded. —Low perennials, with opposite leaves on slender petioles, and small whitish flowers in racemes, produced in summer. (Named for Circe, the enchantress.)

C. lutetiana L. Tall (3-9 dm. high); leaves ovate, tending to ovate-oblong, mostly rounded at the base, of rather firm texture, slightly toothed; 7 bracts none; hairs of the roundish pyriform 2-celled fruit bristle-like (rarely wanting). Common in dry open woods, N. S. to Ont., and southw. (Eu.)