Category: Asteraceae

  • Golden Ragwort (Senecio aureus)

    Golden Ragworts are attractive flowers, a bit like a yellow aster, that bloom in the middle spring, just after the tulips in your garden. The heart-shaped basal leaves and the pinnately lobed (rather fern-like) stem leaves are distinctive. They like a somewhat shady location; these were blooming in early May beside a wooded country lane west of Cranberry.

    Gray (with help from J. M. Greenman) describes the genus and the species:

    SENECIO [Tourn.] L. GROUNDSEL. RAGWORT. SQUAW-WEED. Revised Bt J. M. Greenman. Heads many-flowered; rays pistillate or none; involucre cylindrical to bellshaped, simple or with a few bractlets at the base, the bracts erect-connivent. Receptacle flat, naked. Pappus of numerous very soft and capillary bristles.— Ours herbs, with alternate leaves and solitary or eorymbed heads. Flowers chiefly yellow. (Name from senex, an old man, alluding to the hoariness of many species, or to the white hairs of the pappus.)

    S. aureus L. (GOLDEN R. ) Stems erect from rather slender rootstocks, 3-8 dm. high, at first often lightly floccose-tomentose, soon glabrate; lower leaves long-petioled, ovate-rotund to slightly oblong, 1.5-8 cm. long, two thirds as broad, crenate-dentate; stem-leaves lyrate to laciniate-pinnatifid; the uppermost sessile, amplexicaul, often bract-like; inflorescence cymose-corymbose; heads radiate; rays yellow; achenes glabrous. — In wet meadows, moist thickets, and swamps, Nfd., s. to Va., w. to Wisc., Mo., and Ark. May-Aug.

     

  • Groundsel (Senecio vulgaris)

    As the specific name vulgaris implies, there is nothing unusual about Groundsel; but even for this opportunistic bloomer, there is something unusual about seeing flowers and ripe seeds in early February. Groundsel can take advantage of a very brief break in the weather to bloom, and the warm winter this year has given it the chance to burst into bloom all over.

    Gray describes the genus and the species—but we should not take what he says about the blooming season too seriously.

    SENECIO [Tourn.] L. Groundsel. Ragwort. Squaw-weed. Heads many-flowered; rays pistillate or none; involucre cylindrical to bellshaped, simple or with a few bractlets at the base, the bracts erect-connivent. Receptacle flat, naked. Pappus of numerous very soft and capillary bristles.— Ours herbs, with alternate leaves and solitary or corymbed heads. Flowers chiefly yellow. (Name from senex, an old man, alluding to the hoariness of many species, or to the white hairs of the pappus.)

    Annuals (rarely becoming biennial); stems leafy to the Inflorescence; heads medium-sized, 1 сш. or less high during anthesis.

    S. vulgàris L. (Common Groundsel.) Low annual, 1-6 dm. high. corymbosely branched, glabrate, leafy to the inflorescence; leaves pinnatifid and toothed, 1-8 cm. long, 0.6-3 cm. broad; calyculate bracts (bracteoles) of the involucre distinctly black-tipped; rays none; achenes hirtellous. — Waste grounds, common. July-Sept. (Nat. from Eu.)

  • Tall Thoroughwort (Eupatorium altissimum)

    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:

    EUPATÒRIUM [Tourn.] L. THOROUGHWORT. Heads discoid, 3-many-flowered ; flowers perfect. Involucre cylindrical or bell-shaped, of more than 4 bracts. Receptacle flat or conical, naked. Corolla 6-toothed. Achenes 6-angled; pappus a single row of slender capillary barely roughish bristles. —Erect perennial herbs, often sprinkled with hitter resinous dots, with generally corymbose heads of white, bluish, or purple blossoms, appearing near the close of summer. (Dedicated to Eupator Mithridates, who is said to have used a species of the genus in medicine.)

    EUPATORIUM proper. Receptacle flat.

    Heads 3-20-flowered; involucre of 8-15 more or less imbricated and unequal bracts, the outer ones shorter; flowers white or nearly so.

    Leaves sessile or nearly so, xcith a narrow base, mostly opposite; heads mostly 5-flowered.

    Bracts not scarious or only obscurely so, obtuse, at length shorter than the flowers.

    E. altissimum L. Stem stout and tall, 1-2 m. high, downy; leaves lanceolate, tapering at both ends, conspicuously 3-nerved, entire, or toothed above the middle, 0.5-1.3 dm. long, the uppermost alternate; corymbs dense; bracts of the involucre obtuse, shorter than the flowers. — Dry soil, Pa. to Minn., Neb., and southw.

  • Spotted Knapweed (Centaurea maculosa)

    These beautiful flowers, close relatives of the garden Bachelor’s Button (Centaurea cyanus), seem to be found almost exclusively along railroads. We have three pictures now of this species, each beside a different railroad; this particular plant was part of a colony growing by the railroad viaduct that separates the South Side Flats from the Slopes, where it was blooming at the end of July. (The other two pictures are here and here.)  The color is variable from purple through white, but this purplish pink is by far the most common color.

    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.)

  • Spotted Joe-Pye-Weed (Eupatorium maculatum)

    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.