The very similar, and indeed almost indistinguishable, S. montanum is also known from Westmoreland County, but not Allegheny County; our best bet, therefore, is that this plant is S. angustifolium.

Gray describes the genus and the species (and, by the way, it seems etymologically implausible to describe the name of the genus as “meaningless,” even if we don’t happen to know what it meant):

SISYRÍNCHIUM L. BLUE-EYED GRASS. Sepals and petals (perianth) alike, spreading. Capsule globular, 3-angled. Seeds globular. — Low slender perennials, with fibrous roots, grassy or lanceolate leaves, 2-edged or winged stems, and fugacious umbeled-clustered small flowers from a usually 2-leaved spathe. (A meaningless name, of Greek origin.)

S. angustifölium Mill. Erect or ascending, stiff, glaucous, 1-5 dm. high; the simple (rarely forked) stems 1.5-3 mm. wide, distinctly winged, exceeding the scarcely broader leaves; spathes green, rarely purplish, the outer bract with margins united 3-6 mm. above the base, 2-6.5 cm. long, the inner 1-3 cm. long; perianth violet (rarely white); capsules dull brown or purple-tinged. — Meadows, fields, and damp sandy soil, Nfd. to B. C, s. to Va., Pa., Mich., Minn.; and in the Rocky Mts. May-July.

In his Field Book of American Wild Flowers, Mathews gives us this description:

A stiff grasslike little plant with linear, pale blue-green leaves less than the somewhat twisted and flat flower-stem in height. The flowers are perfect, with a prominent pistil, and three stamens; the six divisions are blunt and tipped with a thornlike point; they are violet-blue, or sometimes white; the centre of the flower is beautifully marked with a six-pointed white star accented with bright golden yellow, each one of the star-points penetrating the deeper violet-blue of the petallike division. The flower is mostly cross-fertilized by bees, and thft beelike flies (Syrphidce). Seed capsule globular. The name is Greek in origin, and is meaningless. 6-13 inches high. In fields and moist meadows, common from Me., south to Va., and west. Stem inch wide.

In the fall this unassuming little weed can take on some surprisingly beautiful and varied autumn colors in the bronze range. This little patch grew out of a crack in a concrete driveway in Beechview, where it was beginning to show off its autumn colors (and its triple seeds) in late September. It grows everywhere in the city, although normally we don’t notice it much.

Gray describes the genus and the species:

ACALYPHA L. THREE-SEEDED MERCURY. Flowers monoecious; the sterile very small, clustered in spikes; the few or solitary fertile flowers at the base of the same spikes, or sometimes in separate ones. Calyx of the sterile flowers 4-parted and valvate in bud; of the fertile, 3-5-parted. Corolla none. Stamens 8-16; filament short, monadelphous at base; anther-cells separate, long, often worm-shaped, hanging from the apex of the filament. Styles 3, the upper face or stigmas cut-fringed (usually red). Capsule separating into 3 globular 2-valved carpels, rarely of only one carpel. — Herbs (ours annuals), or in the tropics often shrubs, resembling Nettles or Amaranths; the leaves alternate, petioled, with stipules. Clusters of sterile flowers with a minute bract; the fertile surrounded by a large and leaf-like cut-lobed persistent bract. (Akalyphe, an ancient name of the Nettle.)

Fruit smooth or merely pubescent; seeds nearly smooth.

A. virginica L. Smoothish or hairy, 3-6 dm. high, often turning purple; leaves ovate or oblong-ovate, obtusely and sparsely serrate, long-petioled; sterile spike rather few-flowered, mostly shorter than the large leaf-like palmately 5-9-cleft fruiting bracts: fertile flowers 1-3 in each axil. — Fields and open places, N. S. to Ont. and Minn., s. to the Gulf. July-Sept.

Our broad modern highways seem to have been the making of this plant around here. It likes the median strips of interstate highways better than any other environment, and its grey-green leaves topped with dusty white flowers make it a decorative companion to the goldenrods that often grow in the same places. The plant above was growing along the side of a highway near Rostraver; the one below in a vacant lot in West Mifflin; both were blooming in late September.

Flower heads. Rayless, white, borne in layers of flat-topped clusters.

Leaves. Dark greyish-green; lanceolate; the upper ones entire, the lower toothed past the midpoint; with three prominent parallel veins. Often there are two smaller leaves where the petiole meets the stem.

Stems. Straight and study; greyish-green, paler than the leaves, often with a brown cast toward the base; much branched.

This plant apparently hybridizes with E. serotinum, and is easily confused with it, probably even on this site.

Gray describes the genus and the species:

The generic name is more correctly spelled Buddleja, but the spelling Buddleia is much more familiar to gardeners.

This favorite butterfly-garden plant often seeds itself, and it has a particular affinity for rocky ground, which in the city translates into sidewalk cracks. In the Pacific Northwest, and in Britain (where the climate is similar to our Pacific Northwest), the Butterfly Bush is an invasive weed. Here it’s an occasional volunteer; this plant sprouted near its parent in a front yard in Beechview, where it was blooming in late September.

The most remarkable thing about Butterfly Bush, of course, is the way it attracts hordes of butterflies. It starts blooming in July, and it keeps blooming until frost. For most of that time, it will be surrounded by butterflies, along with hummingbird hawkmoths and occasional hummingbirds.

Flowers. White to deep violet, but most commonly in the pink range, with a distinctive orange throat. Borne in spikes at the ends of the branches.

Leaves. Lanceolate, with small teeth; softly downy; alternate; somewhat greyish green, much paler on the underside.

Stems. Old growth is woody and twiggy; new growth in early summer may sprout vigorously from the base and reach a height of six or seven feet (about 2 m) by July. Often dies back to the ground over winter, but just as often regrows from old branches.

In many ways an attractive vine, but a very invasive one, and all the harder to get rid of because it is covered with sticky prickles. It can cover a huge area quickly, and seems to be found more and more commonly in the Pittsburgh area. Easily mistaken at first glance for a wild cucumber, but distinguishable by the greenish (rather than pure white) male flowers and the deeply five-to-seven-lobed (rather than more shallowly five-lobed) leaves.

Male flowers and female flowers are borne on separate plants; the female flower clusters are similar to the ones on the familiar domestic hops (H. lupulus) used in making beer. (Japanese hops are said to be poor for beer-making.) The male flowers, which stand up above the vines, are the ones you will notice in a large patch.

These vines were growing in Bird Park in Mount Lebanon, where they were blooming in the middle of September.

This plant had not yet commonly escaped when most of the standard references were written, but Britton’s Manual of the Flora of the Northern States and Canada includes it in an appendix:

HUMULUS L. (See Appendix.) Herbaceous perennial rough vines, with broad opposite thin petioled palmately veined leaves, lanceolate membranous stipules, and dioecious axillary flowers, the staminate panicled, the pistillate in ament-like drooping clustered spikes. Staminate flowers with a 5-parted calyx, the segments distinct and imbricated, and 5 short erect stamens. Pistillate flowers in 2′s in the axil of each bract of the ament. consisting of a membranous entire perianth, clasping the ovary, and 2 filiform caducous stigmas. Fruiting aments cone-like, the persistent bracts subtending the compressed ovate achenes. Endosperm fleshy. Embryo spirally coiled. [Name said to be the diminutive of the Latin humus, earth.] Two species, the following [H. lupulus] widely distributed through the north temperate zone, the other [H. japonicus, our current subject] native of northeastern Asia.

Humulus Japonicus Sieb. & Zucc. Japanese Hop. A twining vine, similar to the Common Hop, the leaves deeply pedately 5-7-cleft. Pistillate aments few-flowered, their bracts and bractlets deltoid, acuminate, hispid-pubescent at least on the margins, not glandular. In waste ground, Conn, to D.C. Introduced from Japan. Aug.-Sept.

Gray describes the genus and the species:

CENTAUREA L. STAR THISTLE. Heads many-flowered; flowers all tubular, the marginal often much larger (as it were radiate) and sterile. Receptacle bristly. Involucre ovoid or globose, imbricated; the bracts margined or appendaged. Achenes obovoid or oblong, compressed or 4-angled, attached obliquely at or near the base; pappus setose or partly chaffy, or none. Herbs with alternate leaves; the single heads rarely yellow. (Kentaurie, an ancient Greek plant-name, poetically associated with Chiron, the Centaur, but without wholly satisfactory explanation.)

C. maculosa Lam. Pubescent or glabrate, with ascending rather wiry branches; involucre ovoid-cainpanulate, in fruit becoming open-campanulate; the outer and middle ovate bracts with rather firm points and with 5-7 pairs of cilia at the dark tip; innermost bracts elongate, entire or lacerate; corollas whitish, rose-pink, or purplish, the marginal falsely radiate. Waste places, roadsides, etc., N. E. to N. J. (Adv. from Eu.)

Gray describes the genus and the species:

AGÁSTACHE Clayt. GIANT HYSSOP. Calyx tubular-bell-shaped, 15-nerved, oblique, 5-toothed, the upper teeth rather longer than the others. Upper lip of corolla nearly erect, 2-lobed, the lower 3-cleft, with the middle lobe crenate. Stamens 4, exserted; the upper pair declined, the lower and shorter pair ascending, so that the pairs cross; anther-cells nearly parallel. —Perennial tall herbs, with petioled serrate leaves, and small flowers crowded in interrupted terminal spikes in summer. (From agan, much, and stachys, an ear of corn, in reference to the numerous spikes.) Lophanthus Benth., in part.

UPDATE: An earlier version of this article gave the wrong species name in the title.

Shorter than the more common Hollow Joe-Pye-Weed (E. fistulosum), with flatter cymes, and with leaves commonly in whorls of 4 rather than 6. The two species sometimes grow side by side, as they did here in a damp depression in Schenley Park, where they were both blooming in early August.

Most botanists today place the Joe-Pye-Weeds in the genus Eutrochium, making this Eutrochium maculatum; we keep the more familiar name for the convenience of Internet searchers.

Once again, we turn to Alphonso Wood for a description:

EUPATORIUM.

Dedicated to Eupator, king of Pontus, who first used the plant m medicine.

Flowers all tubular; involucre imbricate, oblong; style much exserted, deeply cleft; anthers included; receptacle naked, flat ; pappus simple, scabrous; achenia 5-angled.—Perennial herbs, with opposite or verticillate leaves. Heads corymbose. Flowers of the cyanic series, that is, white, blue, red, &c., never yellow.

* Leaves verticillate. Flowers purple.

E. Maculatum. (E. purpureum, ß. Darl.) Spotted Eupatorium.

Stem solid, striate, hispid or pubescent, greenish and purple, with numeróos glands and purple lines; the glands on the stem and leaves give out an acrid effluvium in flowering-time: leaves. triple-veined, 3-5 in a whorl.—Low grounds, U. S. and Can. Stem 4-6 ft. high. Leaves petiolate, 6-7 in. by 3-4 in., strongly serrate. Flowers purple. July-Sept.

This magnificent plant, with its domes of dusty-rose flowers on towering stems, is common in damp fields and roadsides everywhere; these plants grew in a moist depression in Schenley Park, side by side with their close cousins the Spotted Joe-Pye-Weeds (E. maculatum). Enlightened gardeners who have space for a few eight-foot towers in their perennial beds are beginning to discover and make use of this plant, which can now be seen in some of Pittsburgh’s most tasteful gardens.

The taxonomy of the Joe-Pye-Weeds seems to be in an awful mess. Alphonso Wood’s Class-Book of Botany seems to be closest to the modern botanists’ classification of this species, so we use Wood’s description here:

EUPATORIUM.

Dedicated to Eupator, king of Pontus, who first used the plant m medicine.

Flowers all tubular; involucre imbricate, oblong; style much exserted, deeply cleft; anthers included; receptacle naked, flat ; pappus simple, scabrous; achenia 5-angled.—Perennial herbs, with opposite or verticillate leaves. Heads corymbose. Flowers of the cyanic series, that is, white, blue, red, &c., never yellow.

* Leaves verticillate. Flowers purple.

E. fistulosum Barratt. (E. purpureum Willd. in part. E. incarnatum Linn., in part. E. purpureum, v. angustifolium T. & G.) Trumpet-weed.—Stem fistulous, glabrous, glaucous-purple, striate or fluted; leaves in about 12 whorls of 6s, largest in the middle of the stem, rather finely glandular-serrate; midvein and veinlets livid purple; corymb globose, with whorled peduncles.—Thickets, U. S. and Can., very abundant in the Western States! Height 6-10 ft., hollow its whole length. Leaves, including the 1″ petiole, 8″ by 2″. Corymb often 1 ft. diam. Flowers purple. The glaucous hue and suffused redness of this majestic plant are most conspicuous in flowering-time. It does not appear to possess the acrid properties of E. maculatum. July—Sept.

Sumacs belong to the same family that gives us Poison Ivy, but also the tropical cashews and mangoes. For the sake of a mango we can forgive the family anything.

This tree was growing at the edge of a field in Seven Fields, where it was showing off its staghorns in late July.

Gray describes the genus and the species, which he places in the Sumac section of the genus Rhus:

RHÚS L. SUMACH. Calyx small, 5-parted. Petals 5. Stamens 6, inserted under the edge or between the lobes of a flattened disk in the bottom of the calyx. Fruit small and indéhiscent, a sort of dry drupe. — Leaves usually compound. Flowers greenish-white or yellowish. (The old Greek and Latin name.)

§ 1. SUMAC DC. (in part). Flowers polygamous, in a terminal thyreoid panicle; fruit globular, symmetrical, clothed with acid crimson hairs; ttou smooth; leaves odd-pinnate. (Not poisonous.)

R. typhina L. (STAGHORN S.) Shrub or tree, 1-10 m. high, with orange-colored wood; branches and stalks densely velvety-hairy; leaflets 11-31, pale beneath, oblong-lanceolate, pointed, serrate. (Ii. hirta Sud worth.) — Dry or gravelly soil, e. Que. to Ont., s. to Ga., Ind., and Ia. June, July. — Apparently hybridizes with the next species. Forma Laciniata (Wood) Kehder. Leaflets and bracts more or less deeply and laciniately toothed. — A frequent form, at least in some cases pathological and with inflorescence transformed in part into contorted bracts (the Dalisca hirta of L.). Forma Dissecta Rehder. Leaves bipinnatifld to bipinnate. — An occasional form, now in cultivation.